Two numbers x and y are in the ratio 5 : 7 and their sum is 36. Then x is -

Answer: Option B

Let x = 5k and y = 7k
Then,
= x + y = 36 ⇒ 5k + 7k = 36
⇒ 12k = 36
⇒ k = 3
∴ x = 5k = 5 × 3 = 15