A water reservoir is 1/5th full and requires 20 liters more to make it 3/5th full. What is the capacity of the reservoir ( in liters)?

A water reservoir is 1/5^th full and requires 20 liters more to make it 3/5^th full. What is the capacity of the reservoir ( in liters)?

A 40

B 30

C 60

D 50

Correct Answer: Option D

Let full tank be X

Then, A/Q,

3X/5 - X/5 = 20

or, (3X - X) / 5 = 20

or, 2X/5 = 20

or, X = 20*5/2 = 100/2 = 50