Let the middle digit be x. Then, 2x = 10 or x = 5.So, the number is either 253 or 352. Since the number increases on reversing the digits, so the hundred's digit is smaller than the unit's digit. Hence, required number = 253.
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.
EXAMIANS