Question

Brett can plow out all the driveways on his street with his new​ four-wheel-drive truck in 6 hours. Using a snow blade on a lawn​ tractor, his neighbor can plow out the same number of driveways in 12 hours. How long would it take them to do the work​ together?

Answer 1

4 hours

Explanation:

The truck works twice as fast as a lawn tractor, so is equivalent to 2 of them. Together, they are equivalent to 3 lawn tractors, so can do the job in 1/3 the time of one of them: 4 hours.