SOLUTION: J-za is twice as old as his friend Peter. Peter is 5 years older than Alice. In 5 years, J-za will be three times as old as Alice. How old is Peter?

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Question 1147372: J-za is twice as old as his friend Peter. Peter is 5 years older than Alice. In 5 years, J-za will be three times as old as Alice. How old is Peter?
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
J-za, 2p
Peter, p
Alice, a

The description:
system%28p=a%2B5%2C2p%2B5=3%28a%2B5%29%29
-
a=p-5
-
2p%2B5=3%28p-5%2B5%29
cross%282p=3p%29
2p%2B5=3p
highlight%285=p%29

Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.

            At the end of his post,  @josgarithmetic assumes about his solution/answer  "Possible mistake,  or Peter is aged  0."

            I confirm:   Yes, it is a mistake.   There is no doubt - as usual.  Just N3 wrong solution for today.

            So,  I came to provide a correct solution and correct answer. 


J-za, 2p

Peter, p

Alice, a


The description:

system%28p=a%2B5%2C2p%2B5=3%28a%2B5%29%29


From the first equation, express  a = p-5  and substitute it into the second equation.  You will get


2p+5 = 3(p-5+5)

2p + 5 = 3p

5 = 3p - 2p

5 = p


ANSWER.  Peter is 5 years old.

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After my notice, @josgarithmetic successfully re-wrote my answer.