A big container is 50% full with water. If 20 liters of water is added, the container becomes 3/4 full. What is the capacity of the big container in liters?
Choose the correct choice from the following answers:
A) 80
B) 90
C) 100
D) 110
E) 120

Rationale: "20 liters is 25 % of the capacity c . 20 = 0.25 c c = 80 liters . the answer is a ."
Answer: A