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Janet can wax her car in 2 hr(s). When she works together with Helga, they can wax the car in 45
min(s). How long would it take Helga, working by herself, to wax the car?

please help

Respuesta :

Answer:

1.2h / 72min

Step-by-step explanation:

Maria waxes her car in 2 hours. When she works with Susan, they can wax the car

in 45 mins. How long will it take Susan, working by herself, to wax the car?

:

Let x = time required by Susan by herself

:

Change 45 min to hrs: 45/60 = .75 hrs

:

Let the completed job = 1

:

Each will do a fraction of the job and will add up to 1

:

.75%2F2 + .75%2Fx = 1

Multiply equation by 2x to eliminate the denominators, solve for x

 

.75x + 2(.75) = 2x

:

.75x + 1.5 = 2x

:

1.5 = 2x - .75x

:

1.5 = 1.25x

x = 1.5%2F1.25

x = 1.2 hrs (72min), for Susan to do the job by herself

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