Saludos.
Código PHP:
<script language="javascript">
function seleccion(){
tamanop = document.getElementById('tamanop').value;
tippapel = document.getElementById('tippapel').value;
tipimpre = document.getElementById('tipimpre').value;
document.getElementById('total').value = '';
<!--Tamaño BNCarta-->
if((tamanop == "Carta") && (tippapel == "Papel Bond") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 0.5;
else if((tamanop == "Carta") && (tippapel == "Opalina120") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 0.7;
else if((tamanop == "Carta") && (tippapel == "Opalina225") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 1.4;
else if((tamanop == "Carta") && (tippapel == "Couche120") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 0.7;
<!--Tamaño BNOficio-->
if((tamanop == "Oficio") && (tippapel == "Papel Bond") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 0.7;
else if((tamanop == "Oficio") && (tippapel == "Opalina120") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 1.0;
else if((tamanop == "Oficio") && (tippapel == "Opalina225") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 2.0;
else if((tamanop == "Oficio") && (tippapel == "Couche120") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 0.9;
<!--Tamaño BNDoble Carta-->
if((tamanop == "DobleCarta") && (tippapel == "Papel Bond") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 1.2;
else if((tamanop == "DobleCarta") && (tippapel == "Opalina120") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 1.2;
else if((tamanop == "DobleCarta") && (tippapel == "Opalina225") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 2.4;
else if((tamanop == "DobleCarta") && (tippapel == "Couche120") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 1.4;
<!--Tamaño BNDoble Carta-->
if((tamanop == "DobleCarta") && (tippapel == "Papel Bond") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 1.2;
else if((tamanop == "DobleCarta") && (tippapel == "Opalina120") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 1.2;
else if((tamanop == "DobleCarta") && (tippapel == "Opalina225") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 2.4;
else if((tamanop == "DobleCarta") && (tippapel == "Couche120") && (tipimpre == "Blanco y Negro"))
document.getElementById('total').value = 1.4;
<!--Tamaño Color-Carta-->
if((tamanop == "Carta") && (tippapel == "Papel Bond") && (tipimpre == "Color"))
document.getElementById('total').value = 9.0;
else if((tamanop == "Carta") && (tippapel == "Opalina120") && (tipimpre == "Color"))
document.getElementById('total').value = 11.0;
else if((tamanop == "Carta") && (tippapel == "Opalina225") && (tipimpre == "Color"))
document.getElementById('total').value = 12.0;
else if((tamanop == "Carta") && (tippapel == "Couche120") && (tipimpre == "Color"))
document.getElementById('total').value = 10.2;
<!--Tamaño Color-Oficio-->
if((tamanop == "Oficio") && (tippapel == "Papel Bond") && (tipimpre == "Color"))
document.getElementById('total').value = 11.5;
else if((tamanop == "Oficio") && (tippapel == "Opalina120") && (tipimpre == "Color"))
document.getElementById('total').value = 12.5;
else if((tamanop == "Oficio") && (tippapel == "Opalina225") && (tipimpre == "Color"))
document.getElementById('total').value = 13.5;
else if((tamanop == "Oficio") && (tippapel == "Couche120") && (tipimpre == "Color"))
document.getElementById('total').value = 11.7;
<!--Tamaño ColorDoble Carta-->
if((tamanop == "DobleCarta") && (tippapel == "Papel Bond") && (tipimpre == "Color"))
document.getElementById('total').value = 15.0;
else if((tamanop == "DobleCarta") && (tippapel == "Opalina120") && (tipimpre == "Color"))
document.getElementById('total').value = 16.0;
else if((tamanop == "DobleCarta") && (tippapel == "Opalina225") && (tipimpre == "Color"))
document.getElementById('total').value = 17.0;
else if((tamanop == "DobleCarta") && (tippapel == "Couche120") && (tipimpre == "Color"))
document.getElementById('total').value = 15.2;
}
function volumentotal(total,volumen){
n1 = parseFloat(total.value);
n2 = parseFloat(volumen.value);
totalvol.value=n1*n2;
totalvol = num.toFixed(2)
}
</script>
<form name="form1" method="post" action="">
<p>
<label for="tamanop">Tamaño de Papel</label>
<select name="tamanop" id="tamanop" onchange="seleccion()">
<option value="Carta">Carta</option>
<option value="Oficio">Oficio</option>
<option value="DobleCarta">Doble Carta</option>
</select>
</p>
<p>
<label for="tippapel">Tipo de Papel</label>
<select name="tippapel" id="tippapel" onchange="seleccion()">
<option value="Papel Bond">Papel Bond</option>
<option value="Opalina120">Opalina 120gm </option>
<option value="Opalina225">Opalina 225gm</option>
<option value="Couche120">Opalina 120gm</option>
</select>
</p>
<p>
<label for="tipimpre">Tipo de Impresión</label>
<select name="tipimpre" id="tipimpre" onchange="seleccion()">
<option value="Color">Color</option>
<option value="Blanco y Negro">Blanco y Negro</option>
</select>
</p>
<p>
<label for="total">Precio Unitario</label>
<input type="text" name="total" id="total">
</p>
<p>
<label for="volumen">Volumen:</label>
<input name="volumen" type="text" id="volumen" value="0" size="20" maxlength="20" />
</p>
<p>
<label for="totalvol">Precio Total:</label>
<input name="totalvol" type="text" id="totalvol" size="15" maxlength="20"" />
</p>
<p>
<input name="calcular" type="button" id="calcular" onClick="volumentotal()" value="Calcular">
<input type="reset" name="borrar" id="borrar" value="Borrar Datos">
</form>