Twice the difference between two numbers is equal to their sum. If one number is 15, find the other number.

Question

Question

This question was previously asked in

NTPC Tier I (Held On: 30 Mar 2016 Shift 3)

Answer 1

Let the numbers be x and y

From the given data, we get

⇒ 2 (x – y) = x + y

Case 1

When, x = 15

⇒ 2 (15 – y) = 15 + y

⇒ 30 – 2y = 15 + y

⇒ 15 = 3y

⇒ y = 5

Case 2

When, y = 15

⇒ 2 (x – y) = x + y

⇒ 2 (x - 15) = x + 15

⇒ 2x - 30 = x + 15

⇒ x = 45

∴ The other number is either 5 or 45

Confusion PointsIn the question it is asked to find the other number and other numbers may be 5 or 45

It is not asked about the first number so 15 and 45 is not the correct answer.