Answer:
Explanation:
This is a system of inequalities problem. We first need to determine the expression for each phone plan.
Plan A charges $15 whether you use any minutes of long distance or not; if you use long distance you're paying $.09 per minute. The expression for that plan is
.09x + 15
Plan B charges $12 whether you use any minutes of long distance or not; if you use long distance you're paying $.15 per minute. The expression for that plan is
.15x + 12
We are asked to determine how many minutes of long distance calls in a month, x, that make plan A the better deal (meaning costs less). If we want plan A to cost less than plan B, the inequality looks like this:
.09x + 15 < .15x + 12 and "solve" for x:
3 < .06x so
50 < x or x > 50
For plan A to be the better plan, you need to talk at least 50 minutes long distance per month. Any number of minutes less than 50 makes plan B the cheaper one.