If a2 − b2 = 20; a + b = 5, What is the Value of a − b?

If a² − b² = 20; a + b = 5, What is the Value of a − b?

A 3

B 15

C 5

D 4

Correct Answer: Option D

a² − b² = 20
Or, (a + b) (a - b) = 20
Or, 5 × (a - b) = 20
Or, a - b = 20/(a + b)
= 20/5 = 4