Let the number be 10x + y.Therefore, x + y = 9 ..................(i)10x + y - (10y + x) = 4510x + y - 10y - x = 45Therefore, x - y = 5 ..................(ii)From (i) and (ii), x = 7, y = 2Number = 72Therefore, = x x y = 7 x 2 = 14
For a number to be divisible by 4, the number formed by the last two digits of that number must be divisible by 4.For a number to be divisible by 9, the sum of its digits must be divisible by 9.Among the choices, choices (a) and (b) are divisible by 4 but of the first two choices, only choice (b) is divisible by 9.Hence choice (b) is divisible by both 4 and 9.
EXAMIANS