Asked by rojj

The sum of the age of andy and his parents is 72.In how many years time will the sum of their age be 90?
Answered by Steve
(90-72)/2 = 9
Answered by Bosnian
a = Andy's present age

m = Mom's present age

d = Dad's present age


m + d + a = 72


After x years:

Mom will be m + x yrs old

Dad will be d + x yrs old

Andy will be a + x yrs old


m + x + d + x + a + x = 90

m + d + a + 3 x = 90

We know:

m + d + a = 72

So:

72 + 3 x = 90 Subtract 72 to both sides

72 + 3 x - 72 = 90 - 72

3 x = 18 Divide both sides by 3

x = 18 / 3 = 6

After 6 years the sum of their age be 90.








Answered by Steve
I neglected the fact that there were two parents...

Always read the problem carefully!
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