Let x be the total number of liters of apple juice and ginger ale in the punch. Then
x liters - 100%
2 liters - 100%-75%=25%.
Mathematically it can be represented as proportion

If the total number of liters of apple juice and ginger ale in the punch is 8 liters and the punch has 2 liters of ginger ale, then the punch has 8-2=6 liters of apple juice.
Answer: Part A: 8 liters, Part B: 6 liters.