present age of man is 45 years, 5 years back his age was 4 times age of his son what is present age of his son?

Let the present ages of man and son be x and y respectively

x+y = 45

5 yrs ago, age of man = (x-5)

age of son = (y-5)

(x-5) (y-5) = 4 (x-5)

(y-5) = [4 (x-5) ] / (x-5)

y-5 = 4. [ (x-5) got cancelled out]

y = 9 yrs

x+y = 45 yrs

x+9 = 45

x = 45-9 yrs = > 36 yrs