Question

working together, rocco and giulia can paint a room in 3 hours. it would’ve taken rocco 7 hours to do the job alone. which equation can be used to determine r, giulia’s rate of work in parts per hour?

Answer 1

1/7 + r = 1/3

Explanation:

Rocco takes 7 hours to do the job.
In 1 hour, Rocco does 1/7 of the job.

Rocco's rate is 1/7 job per hour.

It takes Giulia x hours to do the job.

In 1 hour, Giulia does 1/x of the job.

Let r = 1/x. Giulia's rate is r part of the job per hour.

Together, Rocco and Giulia take 3 hours to do the job.

In 1 hour, Rocco and Giulia do 1/3 of the job.

Together, their rate is 1/3 of the job per hour.

1/7 + r = 1/3