Dad is (y) years old. Mom is 5 years younger than Dad. What is the total of their ages

Dad is (y) years old. Mom is 5 years younger than Dad. What is the total of their ages

Dad's age:
y

Mom's age (younger means we subtract):
y - 5

The total of their ages is found by adding them together:
y + y - 5

Group like terms, and we get:
2y - 5