SOLUTION: 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. Write two equivalent expressions that

Question 1129578: 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.
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.
Which expression is more useful? Why?

I am in IEP and I don't understand half of my math. Hope you can help me. Thank You
Answer by math_helper(2461) (Show Source): You can put this solution on YOUR website!
Sally is z year old, given

Jane is 2 years older than Sally �> Jane is (z+2) years old

David is 4 times as old as Jane (I reworded, the original wording didn't make sense) �> David is 4*(z+2) years old

These expressions relate the ages of Sally, Jane, and David by expressing those ages in terms of Sally's age.
I don't find any expression more useful than the other, perhaps Sally's age being z is simplest and easiest to work with. For if someone tells you z they are giving you Sally's age straight away.

Sally: z
Jane: z+2
David: 4(z+2)
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