Question

Working alone, Jamie can mow her lawn in 75 minutes. If Bob helps her, then the two

can mow the lawn in 30 minutes. How long does it take Bob to mow the lawn alone?​

Answer 1

• 50 minutes

Explanation:

Jamie's working speed is:

• 1/75 job/min

And Bob's speed is:

• 1/x job/min

Their working speed together is:

• 1/75 + 1/x = 1/30

Solving for x:

• 1/x = 1/30 - 1/75
• 1/x = 5/ 150 - 2/150
• 1/x = 3/150
• 1/x = 1/50
• x = 50

Bob can do the job in 50 minutes