In a division sum, the remainder was 71. With the same divisor but twice the dividend, the remainder is 43. Which one of the following is the divisor ?

Answer: Option C

Let the dividend be (x + 71) and the divisor be y.
Then, [2(x + 71) - 43] is divisible by y
⇒ (2x + 142 - 43) is divisible by y
⇒ (2x + 99) is divisible by y
∴ Divisor = 99

Shortcut method
Divisor = (2 × 71 - 43) = (142 - 43) = 99