The average of X and Y is 40, and the average of Y and Z is What is the value of(X-Z)?

A 5

B 10

C 15

D 20

Correct Answer: Option B

(X + Y) / 2 = 40

or, (X + Y) = 80

Again,

(Y + Z) / 2 = 35

or, (Y + Z) = 70

Now,

(X + Y) - (Y + Z) = 80 - 70

or, X - Z = 10