Answer:
Part 1. x = 20 - y and z = 3y - 4
Part 2. Mike's age = x = 15 years and Joe's age = z = 11 years.
Part 3. Sally's age will then be 10 years.
Step-by-step explanation:
Given that Sally's age is y years.
The sum of Sally's age and Mike's age is 20.
Joe is 4 years less than triple Sally's age.
Part 1.
Therefore, Mike's age is x = 20 - y.
And Joe's age is, z = 3y - 4.
Part 2.
If Sally's age were 5 years, the Mike's age = x = 20 - 5 = 15 years.
And Joe's age = z = 3 ×5 - 4 = 11 years.
Part 3.
If Sally and Mike has the same are i.e. x = y = 20 - y
⇒ 2y = 20
⇒ y = 10 years.
Therefore, Sally's age will then be 10 years. (Answer)
