A cement mason can construct a retaining wall in 16 h. A second mason requires

20 h

to do the same job. After working alone for

8 h,

the first mason quits. How long will it take the second mason to complete the wall?

A mason can construct a retaining wall in 4 h. The mason's experienced apprentice can do the same job in 6 h. How long would it take the mason's novice apprentice to do the job if, working together, all three can complete the wall in 2 h?

Two trains leave the station at the same time heading in opposite directions. The first train is traveling 25 mph faster than the second train. In 7 hours, the trains are 530 miles apart. Find the rate of each train in mph. (Round your answers to the nearest whole number.)first train mph _______________second train mph_________________