Question

Two cell phone companies have different rate plans. Runfast has monthly charges $8 plus $8 per gig of

data. B A &D’s monthly charge is $15 plus $4 per gig of data. Your task is to determine under what
circumstances each company has the better pricing. You will derive and solve a set of equations, graph
those equations, and evaluate the meanings for these events. Don’t worry; I have a series of questions
to guide you through the process. Good luck!
1. Determine the equation for the monthly charges for Runfast and BA&D. (2 points)
Runfast= ______________________
BA&D=________________________
2. Use your mathematical skill to solve this system of equations using the substitution method. (4
points)
Show your work here:

Answer 1

Part 1) The equation for the monthly charges for Runfast is
`y=8x+8` and for BA&D is
`y=4x+15`

Part 2) The solution of the system of equations is the point (1.75.22)

Explanation:

Let

x -----> the number of gig of data

y -----> the total monthly charges

we know that

Runfast Company

`y=8x+8` -----> equation A

BA&D Company

`y=4x+15` -----> equation B

Part 2) Use your mathematical skill to solve this system of equations using the substitution method

we have

`y=8x+8` -----> equation A

`y=4x+15` -----> equation B

Substitute equation B in equation A and solve for x

`4x+15=8x+8`

`8x-4x=15-8`

`4x=7`

`x=1.75\ Gb`

Find the value of y

`y=8(1.75)+8=\$22`

so

The solution is the point (1.75.22)

That means

For the number of gig equal to 1.75 the monthly charge is equal to $22 in both company's

therefore

For a number of gigs less than 1.75 the company Runfast has the better pricing, while for a number of gigs greater than 1.75 the company BA&D has the better pricing