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?

4/21  a room per hour

Step-by-step 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,

step-by-step explanation:

x^2 -12x + 36 + y^2 = 36

x^2 + y^2 = 12x

r^2 = 12rcos(theta)

r = 12 cos(theta)