The SQL at
CONVERT(INT,(12-11)/2)
evaluates to 0 which is causing the result to be 0.75. Whearas the VB.net statement evaluates the same to 0.5.
If the SQL behavior is the intended then you can use the following code.
Dim frm As Decimal = (CInt((12 - 11) / 2)) * 0.05 + 0.75