Question

Megan's text messaging plan costs $15 for the first 500 messages and 5¢ for each additional text message. If she owes $21.55 for text messaging in the month of May, how many text messages did she send that month?

Answer 1

631

Explanation:

This problem can be expressed as:

0.05x + 15 = 21.55
0.05x + 15 - 15 = 21.55 - 15
0.05x = 6.55
0.05x/0.05 = 6.55/0.05
x = 131

We also know that:

0.05x + 15 = x + 500

If x = 131:

x + 500
131 + 500
631