A 3-digit number 4a3 is added to another 3-digit number 984 to give the four-digit number 13b7, which is divisible by 11. Then, (a + b) is :

Answer: Option A

Since 13b7 is divisible by 11, we have,
(7 + 3) - (b + 1) = 0
⇒ 9 - b = 0
⇒ b = 9
Putting b = 9, a + 8 = 9 we get a = 1
Hence, (a + b) = (1 + 9) = 10