Answer:
46 minutes
Explanation:
Sorry about not answering your question sooner, but here is your answer:
In order to get the answer, we have to subtract the original amount of money on the phone card by the amount left ver after the call:
15 - 6.72 = 8.28
Then, we divide this number by 0.18:
8.28 / 0.18 = 46
So, Tammy's call lasted 46 minutes
Hope this helps :)