The question is incomplete:
The telephone company offers two billing plans for local calls. Plan 1 charges $38 per month for unlimited calls and Plan 2 charges $18 per month plus $0.04 per call.
Use an inequality to find the number of monthly calls for which plan 1 is more economical than plan 2.
Answer:
Plan 1 is more economical than plan 2 when you make more than 500 monthly calls.
Explanation:
Plan 1 costs $38 per month for unlimited calls and plan 2 costs $18 per month plus $0.04 per call which is: 18+0.04x and you can infer that plan 1 would be cheaper when you have to pay more than $38 using plan 2 and you can express it with the inequality:
18+0.04x>38, where x is the amount of monthly calls
Now, you can solve for x:
0.04x>20
x>20/0.04
x>500
According to this, plan 1 is more economical than plan 2 when you make more than 500 monthly calls.