If x = y + 4 and x = 20-y, then x2-y2=

If x = y + 4 and x = 20-y, then x²-y²=

A 16

B 80

C 144

D 256

Solution

Correct Answer: Option B

x = y + 4

or, x - y = 4

And,

x = 20 - y

or, x + y = 20

Thus,

x2-y2= (x + y) * (x - y)

= 20 * 4

= 80