Complete the series:
7 + 3 = 28 9 + 3 = 54
6 + 4 = 12 8 + 3 = ?

Explanation

The symbol “+” is being used according to a special rule, not ordinary addition. The pattern is

a+b=a(a-b).
Thus 7+3=7×4=28, 9+3=9×6=54, and 6+4=6×2=12. Therefore 8+3=8×5=40.