There are three goldfish and ten platyfish in a fish tank. Each goldfish plays with ten red balls, while each platyfish plays with five white balls. What is the total number of balls in the fish tank? Let's answer step by step:
If there are 3 goldfish, and each is playing with ten red balls, then the number of red balls in the tank is 3 * 10 = 30. There are also ten platyfish playing with 5 white balls, there are 10 * 5 = 50 white balls. The total number of red and white balls in the fish tank is 50 + 30 = 80. The answer: 80.