posted by Donna .
three teenagers can eat 6 pizzas in half an hour. Assuming that their friends eat at the same rate, how many pizzas can 5 teenagers eat in 90 minutes?
6pizza/(3teen*.5hr) = 4pizza/(teen-hr)
so, that's 4 pizzas per hour per teen
take that and use the given data to get the final number of pizzas:
4pizza/(teen*hr) * 5teen * 1.5hr = 30pizza