
Fred H. answered 01/11/16
Tutor
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Retired ivy league engineer math and english tutor
Let x be the number of weeks until the number of punches on both cards is equal.
Then for each new week, Amy will have 5x new punches on the tea card and x new punches on the coffee card.
Starting with 7 punches on the tea card and 11 punches on the coffee card, the equation below can be used to calculate when the punches are the same.
7 + 5x = 11 + x
4x = 4
x = 1
Therefore, the number of punches on both cards will be equal after 1 week.