You are comparing cell phone providers in order to determine which one offers the best deal. AT&Me offers a plan with a monthly fee of $25, with a $0.10 per minute charge. Tracmyphone offers a plan with a monthly fee of $15, with a $0.15 per minute charge. You typically use less than 100 minutes per month. Your best friend asks for your opinion on which plan is best, but is unsure how many minutes she uses per month. She asks you to give her the parameters which would make each company the better deal so she can decide after she finds out her typical usage.

AT&Me

y=25+0.10x

Tracmyphone

y=15+0.15x

AT&Me

y=25+0.10(100)

y=$35

Tracmyphone

y=15+0.15(100)

y=$30

How can you use the numbers in each function to get more information about each plan?

What does each number you determined mean? How does that tell you which plan is the best for you?

Since your friend does not know how many minutes she typically uses, what information does she need to make her decision?

How can you get all the information from both functions into one equation with only one variable so you can solve it?

When you solve the one variable equation, what information do you have? What do you have to do with it to get other piece of necessary information?

What information would you share with your friend and how will it help her decide on a phone company?