Help with a simple calculation for T-shirt sizes * Quantity * Price

Hello,

I have a form with some drop downs for T-Shirt sizes and Quantities.

I need help figuring out how to calculate the Total Payroll Deduction as seen below.

Basically need a calculation script for both Short Sleeve and Long Sleeve:

Short Sleeve would be something like: Field: Size * Field Quantity * (Price if Size = M or L, Price if Size = XL or XXL)

Long Sleeve would be something like: Field: Size * Field Quantity * (Price if Size = M or L, Price if Size = XL or XXL)

Any help is greatly appreciated.