Let the present age of the father be 'x' and that of the son be 'y'. Then x/y = 8/3∴ 3x = 8y Further, x + 12/y + 12 = 2/1 ∴ x + 12 = 2y + 24 ∴ x - 2y = 12 ......(ii)From eqn (i) and (ii), x = 48, y = 18 ∴ sum = 66 yrs.
Let the ten's digit be x and unit's digit be y. Then, number 10x + y.Number obtained by interchanging the digits = 10y + x.(10x + y) + (10y + x) = 11(x + y)which is divisible by 11.