9514 1404 393
Answer:
50 minutes
Step-by-step explanation:
"Working together" problems like this usually give you the time per task. However, the rates of getting work done add when expressed as tasks per time.
Let b represent the number of minutes Bob takes to mow the lawn alone. Then the sum of lawns mowed per minute is ...
Jamie's rate + Bob's rate = "working together" rate
1/75 + 1/b = 1/30
1/b = 1/30 -1/75
1/b = 5/150 -2/150 = 3/150
1/b = 1/50
b = 50
It takes Bob 50 minutes to mow the lawn alone.
