estoy de acuerdo aqui va?
<form name="form" method="get" action="Grabar" onsubmit="return verifica(this)">
<%
out.println("<input type='text' name='CANT' size='10'>");
%>
<input type="hidden" name="oculto" value='<%=ario%>'>
<%
out.println("<br>");
out.println("<input type='radio' name='OPC' value='abonar'>");
out.println("Abonar");
out.println("<br>");
%>
<input type="radio" name="OPC" value="descontar" onclick="return valida(<%=sal%>)">
<%
out.println("Descontar");
out.println("<br>");
out.println("<input type='submit' name='boton' value='Grabar'>");
out.println("</form>");