If you mean y = 2(x + 3), then you first need to expand the brackets and get 2x + 6. If x = 5, then 2 × 5 = 10 and 10 + 6 = 16, which would be your answer.
If by y = (x + 3)2 you mean y = (x + 3) + 2, then 5 + 3 = 8, and 8 + 2 = 10, which would be your answer.
I hope this helps!
