Question 614316
boy's age  be x
and father's age =y
{{{x/y = 1/4}}}
so y= 4x
In 4 years their ages will be
x+4 & y+4

{{{(x+4)/(y+4) = 1/3}}}
cross multiply
3(x+4) = (y+4)
substitute y 

3x+12=4x+4
4x-3x=12-4
x=8 the boy's age