SOLUTION: A basic cellular package costs $30/month for 60 minutes of calling with an additional charge of $0.50/minute beyond that time. The cost function C(x) for using x minutes would be

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons  -> Linear Equations Lesson -> SOLUTION: A basic cellular package costs $30/month for 60 minutes of calling with an additional charge of $0.50/minute beyond that time. The cost function C(x) for using x minutes would be       Log On


   

Question 1173391: A basic cellular package costs $30/month for 60 minutes of calling with an additional charge of $0.50/minute beyond that time. The cost function C(x) for using x minutes would be
If you used 60 minutes or less, i.e. if if x≤60, then C(x)=30 (the base charge).
If you used more than 60 minutes, i.e. (x−60) minutes more than the plan came with, you would pay an additional $0.50 for each of those (x−60) minutes. Your total bill would be C(x)=30+0.50(x−60).

If you want to keep your bill at $50 or lower for the month, what is the maximum number of calling minutes you can use?
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


30%2B0.50%28x-60%29+%3C=+50
0.50%28x-60%29+%3C=+20
x-60+%3C=+40
x+%3C=+100

ANSWER: 100 minutes

Informally (good mental exercise!):

$30 basic charge leaves $20 for minutes above 60.

$20 at $0.50 per minute ($1 per 2 minutes) means 2*20=40 minutes above 60.

So the total number of minutes is at most 60+40 = 100.