Question

there are 720 dishes that need to be rinsed. john can rinse them in 120 minutes by himself. it will take his friend rafael 72 minutes to rinse these dishes. how long will it take them if they rinse these 720 dishes together? minutes

Explanation:

Step1: Calculate John's rate

John can rinse 720 dishes in 120 minutes. His rate is $\frac{720}{120}=6$ dishes per minute.

Step2: Calculate Rafael's rate

Rafael can rinse 720 dishes in 72 minutes. His rate is $\frac{720}{72} = 10$ dishes per minute.

Step3: Calculate their combined rate

The combined rate of John and Rafael is $6 + 10=16$ dishes per minute.

Step4: Calculate the time taken together

To rinse 720 dishes at a rate of 16 dishes per minute, the time taken is $\frac{720}{16}=45$ minutes.

Answer:

45