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=<<3*10=30>>30
There are also ten platyfish playing with 5 white balls, there are 10*5= <<10*5=50>>50 white balls.
The total number of red and white balls in the fish tank is 50+30 = <<50+30=80>>80
#### 80