No se mucho de Basic asi que seguramente hay formas mas faciles de hacerlo, pero que te mando el codigo, espero que te sirva.
Código vb:
Ver originalPublic Sub separar(ByVal exp As String)
Dim varible1 = ""
Dim operador = ""
Dim varible2 = ""
Dim igual = ""
Dim resultado = ""
Dim encontro As Boolean = False
Dim i = 0
While exp.Substring(i, 1) <> "="
If encontro = False Then
varible1 = varible1 + exp.Substring(i, 1)
End If
If exp.Substring(i, 1) = "+" Or exp.Substring(i, 1) = "-" Or exp.Substring(i, 1) = "/" Or exp.Substring(i, 1) = "*" Then
operador = exp.Substring(i, 1)
encontro = True
End If
If encontro = True Then
varible2 = varible2 + exp.Substring(i, 1)
End If
i = i + 1
End While
igual = "="
varible1 = varible1.Substring(0, varible1.Length - 1)
varible2 = varible2.Substring(1, varible2.Length - 1)
resultado = exp.Substring(varible1.Length + varible2.Length + 2, exp.Length - varible1.Length - varible2.Length - 2)
TextBox2.Text = varible1
TextBox3.Text = operador
TextBox4.Text = varible2
TextBox5.Text = igual
TextBox6.Text = resultado
End Sub