The expression that can be use to find Amy's age is (3 × 7) – 4.
Solution:
Age of Ginger = 7 years
Age of Amy = 4 years younger than 3 times Ginger's age
To write this statement as expression:
Ginger's age = 7
3 times Ginger's age = 3 × 7
4 years younger than 3 times Ginger's age = (3 × 7) – 4
Hence the expression that can be use to find Amy's age is (3 × 7) – 4.