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

Answer: B

Step-by-step explanation:

Rocco: $\dfrac{1}{7}$ of the job per hour

Giulia: $\dfrac{1}{x}$ of the job per hour

Together: $\dfrac{1}{3}$ of the job per hour

Rocco + Giulia = Together

$\dfrac{1}{7}$ + $\dfrac{1}{x}$ = $\dfrac{1}{3}$

$\dfrac{1}{7}(21x)$ + $\dfrac{1}{x}(21x)$ = $\dfrac{1}{3}(21x)$

3x + 21 = 7x

       21 = 4x

       $\dfrac{21}{4} = x$

It will take Giulia $\dfrac{21}{4} = 5\dfrac{1}{4}$ hours to paint the room by herself.

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Giulia: $r=\dfrac{1}{x}$ = $\dfrac{4}{21}$

A) $\dfrac{3}{7} + 3(\dfrac{4}{21}) = 7$

    $\dfrac{3}{7} + \dfrac{4}{7} = 7$

    $\dfrac{7}{7} = 7$  

    1 = 7

    FALSE

B) $\dfrac{3}{7} + 3(\dfrac{4}{21}) = 1$    

   $\dfrac{3}{7} + \dfrac{4}{7} = 1$

    $\dfrac{7}{7} = 1$  

    1 = 1

    TRUE

Answer 2

Answer:

b is the correct answer for edge

Step-by-step explanation: