This is a simple division series. Each number is divided by 5. Rule = (1st number / 5 = 2nd number) (2nd number / 5 = 3rd number)....Now, (1000 / 5 = 200), (200 / 5 = 40), (40 / 5 = 8)...So answer is a = 8.
Let the father's age be x and son's age yTherefore, x + y = 60 ....................(i)Five years back, (x - 5) = 4 (y - 5)x - 4y = - 15 ......................(2)Solving (1) and (2), x = 45 and y = 15
EXAMIANS