Christine purchased a prepaid phone card for $30. Long distance calls cost 18 cents a minute using this card. Christine used her card only once to make a long distance call. If the remaining credit on her card is $27.84, how many minutes did her call last?

The answer is 12 minutes.

Step-by-step explanation:

It is given that the cost of one minute is $0.18. Firstly, you have to substract the remaing credits from her original credits :

$30 - $27.84 = $2.16

We have found out that she uses $2.16 for her long distance call. Next, you have to divide 18 cents from the uses in order to find out how many minutes she use :

the volume is the product of the area of the base, 3x(3x+4), and the height, 3x-1

step-by-step explanation: