Question

Melissa purchased a prepaid phone card for $30. Long distance calls cost 21 cents a minute using this card. Melissa used her card only once to make a longdistance call. If the remaining credit on her card is $21.81, how many minutes did her call last?minutes

Answer 1

Let's review the information given to us to answer the exercise correctly:

Amount in Melissa's prepaid card = $ 30

Price per minute of long distance calls = $ 0.21

Balance of Melissa's prepaid card = $ 21.81

Step 1: Write the equation to find the number of minutes Melissa used on her long distance call, as follows:

Let x to represent the number of of minutes Melissa used on her long distance call

Amount of prepaid card - Number of minutes Melissa talked = Balance of the prepaid card

Replacing with the values we know, we have:

30 - 0.21x = 21.81

Step 2: Solve for x

-0.21x = 21.81 - 30

-.021x = - 8.19

Dividing by -0.21 at both sides:

-0.21x/-0.21 = -8.19/-0.21

x = 39

Step 3: Interpret the result for x

Melissa used her phone card for 39 minutes