Bill can mow the lawn in 2 hours, and his younger brother Tom can mow it in 3 hours. If both brothers mow the lawn together, how many hours will it take them?

We have a work problem right here. We can use knowledge on ration and proportion to answer this type of problem. We do as follows:

1 job / 2 hours + 1 job / 3 hours = 1 job / time it takes for both when working together

time it takes for both when working together = 1.2 hours