Or, you could just use DIV32. And, make sure Temp2 is a WORD.
Code:
Temp2 var word
Temp3 var word

Temp3 = (MasterVolume * 128) / 100
Temp2 = TrimLeft * 10
Temp2 = Temp2 * Temp3 
Temp2 = DIV32 500
Temp2 = Temp2 + Temp3
HTH,
   Darrel