Linear Equation Real World

A T-shirt design company charges your team an initial fee of $25 to create the team's design. Each t-shirt printed with your design costs an additional $8. The equation for this situation is y = 8x + 25. Interpret the y-intercept in context.

• The additional fee of $8.

• The initial fee of $25.

• The additional fee of $25.

• The initial fee of $8.

A cell phone company charges $60.00 a month for up to 1 gigabyte of data. The cost of additional data is $0.05 per megabyte. If d represents the number of additional megabytes used and c represents the total charges at the end of the month, which linear equation can be used to determine a user's monthly bill?

• c = 60 − 0.05d

• c = 60.05d

• c = 60d − 0.05

• c = 60 + 0.05d

Peyton is signing up for a gym membership with a one-time fee to join and then a monthly fee to remain a member. The total cost of the gym membership, C, over t

months whose graph is shown below.

Write an equation for C in terms of t. (hint: use y=mx+b)

• C=40t+150

• C=-40t+150

• C=50t+150

• C=50t-150

When Isabella left her house in the morning, her cell phone battery was partially charged. The charge remaining in Isabella's battery,B, a as a percentage can be modeled by the graph shown below where t represents the time. Write an equation using slope-intercept form to model this situation.

• B= 90t+10

• B=10t+90

• B=-10t+90

• B=-90t+10

The Roaming Cell Phone Company charges $15.00 per month plus $0.20 per minute of airtime usage. If Juanita uses x minutes of airtime, what is an equation that can be used to determine her monthly cell phone bill? The equation is y=0.20x+15. What does the y mean?

• amount of minutes

• total cost

• cost per minute

• variable

• flat fee

The cost, c, to park in a parking garage can be represented using the equation c = 5 + 0.5h, where h is the number of hours the car is in the parking garage. Which of these statements is TRUE?

• It costs $0.50 to park in the garage for 1 hour.

• It costs $5 to park in the garage for 1 hour.

• It costs $5 per hour to park in the garage.

• It costs $6 to park in the garage for 2 hours.

Mathematical Equivalence

ON

Answer explanation

y = x + 8 | This tree is 8 feet tall and growing 1 foot each year.

y = x/2 + 10 | This tree is 10 feet tall and growing 1/2 foot each year.

Substitute x + 8 for y in 2nd equation

x + 8 = x/2 + 10

x - x/2 + 8 -8 = x/2 - x/2 + 10 -8

x/2 = 2 | x = 4 years

Joe’s Canoes charges an initial fee of $20 plus $4 an hour. Callie’s Canoes charges a flat rate of $14 an hour. Find the number of hours for which the total amount that both places charge would be the same.

• 3 hours

• 4 hours

• 1 hour

• 2 hours

• $9

• $15

• $24

• $39

Each month Chuck’s phone company charges a flat fee of $12 plus $0.05 per minute. Louie’s phone company charges him a flat fee of $6 plus $.85 per minute. How many minutes would the boys have to talk for their phone bill to be the same?

• 7 minutes

• 7 minutes and 30 seconds

• 8 minutes

• 8 minutes and 30 seconds