Question: A mixture of two liquids A and B is in the ratio 4:3. If 21 liters of liquid A is added to the mixture, the ratio becomes 5:3. What was the initial volume of the mixture?
Options:
Correct Answer: 45 liters
Solution:
Let the initial volumes of A and B be 4x and 3x. After adding 21 liters to A, we have (4x + 21)/(3x) = 5/3. Solving gives x = 15, so the initial volume = 4x + 3x = 45 liters.