SOLUTION: a father was 30 years old when his son was born,he is now 3 times as old as his son.Find their present age.In how many years will the son be half as old as his father.

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Question 892888: a father was 30 years old when his son was born,he is now 3 times as old as his son.Find their present age.In how many years will the son be half as old as his father.
Found 2 solutions by josgarithmetic, lwsshak3:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
_____________SON's BIRTH______________NOW
FATHER________30______________________y+30
SON____________0_______________________y

From birth to now was passage of y years.
NOW, y%2B30=3%2Ay
30=3y-y
2y=30
highlight%28y=15%29------The son's age now.
-
y%2B30=15%2B30=highlight%2845%29-------The father's age now.

Starting from now, when will son be half his father's age?
Let w = how many years pass from now.
highlight_green%2815%2Bw=%281%2F2%29%2845%2Bw%29%29----Solve for w.

Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
a father was 30 years old when his son was born,he is now 3 times as old as his son.Find their present age.In how many years will the son be half as old as his father.
***
let x=son's present age
30+x=father's present age
..
30+x=3x
2x=30
x=15
30+x=45
son's present age=15
father's present age=45
..
let y=years son will be half as old as his father
15+y=(45+y)/2
30+2y=45+y
y=15
In how many years will the son be half as old as his father. 15