Question

Working together, Rocco and Giulia can paint a room in 3 hours. It would have 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

B

Step-by-step explanation:

Rocco: of the job per hour

Giulia: of the job per hour

Together: of the job per hour

Rocco + Giulia = Together

+ =

+ =

3x + 21 = 7x

21 = 4x

It will take Giulia hours to paint the room by herself.

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Answer 2

4/21 a room per hour

Explanation:

Rocco :

7hours———> whole room

then

in 1h ———-> 1/7 of the whole room

then

in 3h ———-> 3/7 of the whole room

therefore

Giulia will finish 4/7 of the whole room in 3h

finally,

`r=((4)/(7) )/(3) =(4)/(21)`