Answer:
son is 5 years old
Explanation:
let the son's age be n when father is 41 years old
in 7 years
son will be n + 7 and father will be 41 + 7 = 48
at this time the father is 4 times as old as his son, that is
4(n + 7) = 48 ( divide both sides by 4 )
n + 7 = 12 ( subtract 7 from both sides )
n = 5
that is the son is 5 years old