If 20 volunteers can wash 100 cars in 2.5 hours, find the constant of variation and find out how many cars 30 volunteers can wash in 3 hours?

20 volunteers ... 100 cars ... 2,5 h

1 volunteer ... 100 cars ... 2,5*20=50 h

1 volunteer ... 100:50=2 cars ... 1h

1 volunteer ... 2*3=6 cars ... 3h

30 volunteers ... 6*30=180 cars ... 3h

Answer: 180 cars