SOLUTION: Next year Peter will be twice as old as his sister will be. She is three years younger than he. How old is each one now?

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Question 310882: Next year Peter will be twice as old as his sister will be. She is three years younger than he. How old is each one now?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
P-Peter's age right now
S-Sister's age right now
Next year, Peter will be P%2B1, Sister will be S%2B1.
1.P%2B1=2%28S%2B1%29
2.S=P-3
Substitute eq. 2 into eq. 1,
P%2B1=2%28P-3%2B1%29
P%2B1=2%28P-2%29
P%2B1=2P-4
-P=-5
highlight%28P=5%29
Then from eq. 2,
S=P-3=5-3
highlight_green%28S=2%29
Peter is 5 years old, his sister is 2 years old.