Question 969546
Let x = number of years required.

Father is 41 +x at that time
Son is 9 +x  at that time

Father is 3 times the son's age.

therefore 3(9+x)=41 +x
Distribute the 3

27 +3x=41 +x

Subtract 27 from both sides

3x=14 +x
Subtract x from both sides

2x=14
Divide both sides by 2

x=7

In 7 years, the father will be 48
In 7 years the son will be 16

48/16  = 3