Carrie can inspect a case of watches in 5 hours. James can inspect the same case of watches in 3 hours. After working alone for 1 hour, Carrie stops for lunch. After taking a 40-minute lunch break, Carrie and James work together to inspect the remaining watches. How long do Carrie and James work together to complete the job?

Answer: Time = 1.5hours or 1 hour 30minutes

Step-by-step explanation:

Given;

Carrie can inspect a case of watch in 5 hours

if n represent the task,

Carrie's rate C = n/5

James' rate J = n/3

Their combined rate is=n/5 + n/3 = 8n/15

Carrie After working one hour, he would have completed n/5 of the task.

Therefore, the remaining fraction of task is 4n/5

To complete the remaining fraction of task by the two of them, the time taken can be given as;

Work done = rate * time

Time = workdone/rate

Workdone = amount of task remaining = 4n/5

rate combined = 8n/15

Time = (4n/5) / (8n/15)

Time = 1.5hours or 1 hour 30minutes