Answer:
21 cups of water
Explanation:
If he saves 3 cups of water in one time that he turns off the tap while brushig his teeth, we just have to multiply those three minutes for the number of times he will be brushing his teeth, in the problem they tell us that the number of trials will be 7, so we just multiply it by 7:
[tex]Number of cups*NumberofTrials=Total cups\\3 cups*7 trials=21 cups[/tex]
So he will save 21 cups of water in 7 trials.
