Percentage Q20

20.If one number is 80% of the other and 4 times the sum of their squares is 656, then the numbers are:

[A] 4, 5

[C] 16, 20

[B] 8, 10

[D] None of these

Answer : [B]
Explanation :

Let one number = x, Then, other number = 80% of x = 4 5

4  x2 + 4 5 x 2  = 656 x2 +  16 25  x2 = 164 41 25  x2 = 164

x2  =   164 x 25 41  = 100   x = 100

So, the numbers are 10 and 8.