9514 1404 393
Answer:
6 hours
Explanation:
The old machine produces widgets at the rate of ...
(24 widgets)/(3 h) = 8 widgets/h
The new machine produces widgets at the rate of ...
(48 widgets)/(4 h) = 12 widgets/h
The total rate of production of the two machines is ...
(8 +12) widgets/h = 20 widgets/h
Then the time required to produce 120 widgets is ...
(120 widgets)/(20 widgets/h) = 6 h
Working together, the two machines can produce 120 widgets in 6 hours.