Part A.
Consider a punch containing L liters.
60% of these that is
is grape juice, and the rest, 0.4 L is lemon-soda.
so, for the variable L, the total amount of punch, the total amount of grape juice is 0.6 L
and the amount of lemon soda in the punch is 0.4L
Part B.
For L=2, we substitute and get:
0.6 L=0.6 * 2 liters = 1.2 liters of grape juice
0.4 L = 0.4 * 2 liters = 0.8 liters of lemon soda.