a father is 20 years older than his son. five years ago, he was three times as old as his son. find their present age.

Question

 equation

Answer 1

Let F be the father's age and S  be the son's age.

 

The first statement can bebtranskatedas F = S + 20.

 

The second statement is F - 5 = 3(S - 5)

 

Plugging the first equation into the second

 

S + 20 - 5 = 3(S - 5)

S + 15 = 3(S - 5)

S + 15 = 3S - 15

S + 30 = 3S

30 = 2S

15 = S

 

So the son is 15, and the father is 35. 5 years ago, they were 10 and 30.