Question

for his phone service, Chua pays a monthly fee of 25, and he pays an additional $0.05 per minute of use. the least he has been charged in a month is $89.40.what are the possible number of minutes he has used his phone in a month?use M for the number of minutes, and solve your inequality for M

Answer 1

Inequalities

Chua pays a monthly fee of $25 for his phone service, plus $0.05 per minute of use.

Let M = number of minutes Chua uses the phone service.

His monthly cost for the phone service is:

C = 25 + 0.05M

The least he has been charged in a month is $89.40. If we want to know the number of minutes he used the service in that month, then we must solve the inequality:

25 + 0.05M ≥ 89.40

Subtracting 25:

0.05M ≥ 89.40 - 25

Operating:

0.05M ≥ 64.40

Dividing by 0.05:

M ≥ 64.40 / 0.05

M ≥ 1288

He has used his phone service at least for 1288 minutes in a month