SOLUTION: Barry is 8 years older than his sister. In 3 years he will be twice as old as she will be then. How old is each now.

Question 502124: Barry is 8 years older than his sister. In 3 years he will be twice as old as she will be then. How old is each now.
Answer by Maths68(1474) (Show Source): You can put this solution on YOUR website!
Let
Present age of Barry = b
Present age of sister = s
Barry is 8 years older than his sister means if we subtract 8 from present age of Barry both will be of equal age
s=b-8 ............(1)
In 3 years means we have to add 3 in their present age
s+3=b+3
then
he will be twice as old as
2(s+3)=(b+3
2s+6=b+3
2s=b+3-6
2s=b-3...............(2)
Put the value of s from (1) to (2), we have
2(b-8)=b-3
2b-16=b-3
2b-b=-3+16
b=13
Put the value of b in (1)
s=13-8
s=5
Present age of Barry = b = 13
Present age of sister = s = 5

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