Question

David has two younger sisters, Jane and Sally. Jane is 2 years older than Sally and David is 4 times older than Jane. Sally is z years old.

Part A

Write two equivalent expressions that represent David’s age in terms of Sally’s age, z, and explain how the two expressions relate to one another.

Part B

Which expression is more useful? Why?

Answer 1

2+z(4) and 4z+2

Explanation:

The first one is more useful because it has everything in order. How much Jane is older than Sally then, how many times David is older than Jane.

(Hope it's right.)