Answer:
C. Greg weighs 180 pounds, and Justin weighs 165 pounds
Explanation:
let G be the weight of Greg and J be the weight of Justin
G -15=J
G/2 +75=J
G =J+15 (1)
G+150=2J. (2)
If We substitute G by J+15 in equation (2) we will get:
G =J+15
J+15+150=2J
G =J+15
J+15+150=2J
G =J+15
J+165=2J
then J=165 and G=165+15=180