Question

9=90
8=72
7=56
6=42
3=?

Answer 1

3=12 because the number on the left is multiplying by a decreasing number starting at 10

Answer 2

Youre multiplying a digit, x, with (x+1).

9*(9+1)=90
8(8+1)=72
7(7+1)=56
6(6+1)=42
3(3+1)=12