SOLUTION: how could i make a system of equations (2) for this problem: sue is 4 years younger than sally. in 3 years sally will be twice as old as sue. how old are they now?

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Question 62355: how could i make a system of equations (2) for this problem: sue is 4 years younger than sally. in 3 years sally will be twice as old as sue. how old are they now?
Answer by joyofmath(189) About Me  (Show Source):
You can put this solution on YOUR website!
how could i make a system of equations (2) for this problem: sue is 4 years younger than sally. in 3 years sally will be twice as old as sue. how old are they now?
Let S = Sue's Age
Let A = Sally's Age
Then, S=A-4.
Also, A%2B3=2%2A%28S%2B3%29.
Then, A%2B3=2%2A%28A-4%2B3%29.
Or, A%2B3=2%2A%28A-1%29.
Or, A%2B3=2%2AA-2.
Or, A%2B5=2%2AA.
Or, A=5.
So, Sue is 4 years younger than Sally, so Sue is one year old: S=1.
Let's verify the answer:
If Sue is 1 year old then Sally is 5 years old. In 3 years Sue will be 4 years old and Sally will be 8 years old so, indeed, Sally will be twice as old as Sue.