SOLUTION: The age of the father is 5 times the age of his son. After 18 years, the age of the father will be twice his sons age. Find their present ages.

Question 519229: The age of the father is 5 times the age of his son. After 18 years, the age of the father will be twice his sons age. 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
The age of the father is 5 times the age of his son.
f=5s.........(1)
After 18 years,
Age of Father = f+18
Age of Son = s+18
Then, the age of the father will be twice his sons age.
f+18=2(s+18)
f+18=2s+36
f=2s+36-18
f=2s+18............(1)
Substitute the value of f in (2) from (1)
5s=2s+18
5s-2s=18
3s=18
3s/3=18/3
s=6
Substitute the value of s in (1)
f=5s
f=5(6)
f=30

Present age of Father = f = 30 years old
Present age of Son = s = 6 years old

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