Question 1089906
The original amount of the card is $20, and the final amount is $11.18.

So the difference between those two is 20.00 - 11.18 = 8.82.

This means that Mary used $8.82 worth of her phone card when she made the long distance call.  If we know that each minute costs $0.18, how can we figure out how many minutes it takes to use up $8.82 worth of the phone card?

We divide.  $8.82 / $0.18 = 49.

So Mary's long distance phone call had to have lasted 49 minutes.  To check your answer, simply multiply 49 minutes by $0.18 to get the total cost.