Question

HELP ASAP!!! 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?

A- 3/7+3r=7
B- 3/7 + 3r =1
C- 1/7 = R
D- 3/7 = 3r

Answer 1

b is the correct answer for edge

Explanation:

Answer 2

Answer: B

Explanation:

Rocco:
`(1)/(7)` of the job per hour

Giulia:
`(1)/(x)` of the job per hour

Together:
`(1)/(3)` of the job per hour

Rocco + Giulia = Together

`(1)/(7)` +
`(1)/(x)` =
`(1)/(3)`

`(1)/(7)(21x)` +
`(1)/(x)(21x)` =
`(1)/(3)(21x)`

3x + 21 = 7x

21 = 4x

`(21)/(4) = x`

It will take Giulia
`(21)/(4) = 5(1)/(4)` hours to paint the room by herself.

*******************************************************************************************

Giulia:
`r=(1)/(x)` =
`(4)/(21)`

A)
`(3)/(7) + 3((4)/(21)) = 7`

`(3)/(7) + (4)/(7) = 7`

`(7)/(7) = 7`

1 = 7

FALSE

B)
`(3)/(7) + 3((4)/(21)) = 1`

`(3)/(7) + (4)/(7) = 1`

`(7)/(7) = 1`

1 = 1

TRUE