SOLUTION: the ratio of father and his 3 childrens age is 3:1 after 15 years ,the age of the father age will be equal to sum of the ages of the 3 children.what is the present age of the fathe

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Question 900737: the ratio of father and his 3 childrens age is 3:1 after 15 years ,the age of the father age will be equal to sum of the ages of the 3 children.what is the present age of the father?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
let f = the fathers age; let a,b,c be the three kids' ages
:
the ratio of father and his 3 childrens age is 3:1
f = 3(a+b+c)
or
(a+ b + c) = 1%2F3f
:
after 15 years ,the age of the father age will be equal to sum of the ages of the 3 children.
f + 15 = (a+15) + (b+15) + (c+15)
f + 15 = a + b + c + 45
f = a + b + c + 45 - 15
f = a + b + c + 30
replace (a+b+c) with 1%2F3f
f = 1%2F3f + 30
f - 1%2F3f = 30
2%2F3f = 30
multiply both sides by 3
2f = 90
f = 90/2
f = 45 yrs is the fathers age
P:
:
you can check this for yourself, the sum of the kids' age is 15
Find the their sums after 15 yrs (father and 3 kids)