Let the age of the son be x and the age of the father be y.Therefore, x + y = 65 ..........(i)or, 2 x (x + 5) = (y + 5)or, 2x + 10 = y + 5or, 2x - y = 5 ...................(ii)From equations (i) and (ii), x = 20, y = 45
The numbers less than 696 and are squares of certain numbers are 676, 625.The least number that should be subtracted from 696 to make it perfect square = 696 - 676 = 20.