Greetings from Brasil...
The solution to this problem will be to add all the quantities of juice he used to make the punch. Note that all volume units must be the same (we cannot add liters to milliliters. Only liters to liters and milliliters to milliliters). We will work with milliliters
tropical drink = 3,500mL
ginger ale = 3,095mL
pineapple juice = 1,600mL
total = 3,500 + 3,095 + 1,600
total = 8,195mL
(or 8.195L)