Question

If a @ b is defined for all positive integers a and b by the equation a @ b = a(b-a),then 4 @ (3 @ 5)=

1. 2
2. 6
3. 8
4. 22
5. 28

Answer 1

3@5 = 3(5-3) = 6, so

4@(3@5) = 4@6 = 4(6-4) = 8