SOLUTION: a father is 30 years older than his son. in 12 years, the father will be twice as old as his son. find their present ages.

Question 500138: a father is 30 years older than his son. in 12 years, the father will be twice as old as his son. find their present ages.

Answer by Maths68(1474) (Show Source): You can put this solution on YOUR website!
Let
Present age of father = f
Present age of son = s
father is 30 years older than his son means if we add 30 years to the son's age father and so will be of same age
f=s+30............(1)
In 12 years, means we have add 12 in present ages of both
f+12=s+12
then
the father will be twice as old as his son
f+12=2(s+12)
f=2s+24
f=2s+24-12
f=2s+12 .......(2)
Put the value of f from (1) to (2)
s+30=2s+12
s=2s+12-30
s=2s-18
s-2s=-18
-s=-18
Multiply by (-1) both sides of the above equation
s=18
Put the value of s in (1)
f=s+30
f=18+30
f=48
Present age of father = 48
Present age of son = 18

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