SOLUTION: Five years ago, peter was twice as old as Greg. If peter is 21 years old now, how old is Greg

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Question 1113924: Five years ago, peter was twice as old as Greg. If peter is 21 years old now, how old is Greg
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

let's Peter's age be P and Greg's G
if five years ago, Peter was twice as old as Greg, we have
P-5=2G
if Peter is 21 years old now,we have
21-5=2%28G-5%29
16=2G-10
16=2G-10
16%2B10=2G
26=2G
G=13
so, Greg is 13 years old
check:
Peter is 21 and Greg is 13
five years ago Peter was 21-5=16 and Greg was 13-5=8, and you can see that Peter was twice as old as Greg because 16=2%2A8