SOLUTION: mary can wash her car in 40 minutes. TIna can wash the car in 25 minutes. How long will it take to wash the car if both girls work together on the task

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Question 1005044: mary can wash her car in 40 minutes. TIna can wash the car in 25 minutes. How long will it take to wash the car if both girls work together on the task
Answer by ikleyn(52788) About Me  (Show Source):
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Mary can wash her car in 40 minutes. Tina can wash the car in 25 minutes.
How long will it take to wash the car if both girls work together on the task?
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Mary makes 1%2F40 of the entire job per minute.

Tina makes  1%2F25  of the entire job per minute.

Both of them make  1%2F40 + 1%2F25  of the entire job per minute working together.

It is equal to  5%2F200 + 8%2F200 = 13%2F200  of the entire job per minute.

Hence,  they need  200%2F13  minutes to complete the job.

It is  155%2F13  minutes.