Construct Linear Functions from Word Problems

The total cost, y, for a member to see 5 movies, x, is $40 and the total cost to see 12 movies is $75. Assume the relationship is linear. Find the rate of change (slope).

• $8 per movie

• $5 per movie

• $6.25 per movie

• There is no constant rate of change.

Write an equation in y = mx + b for the movie membership above.

• y = 15x + 5

• y = 5x + 15

• y = 5x + 40

• y = 12x + 75

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 (C)?

• C = 0.20x + 15

• C =15 (0.20x)

• C = 15 + x + 0.20

• C = 0.20 + 15x

Sonya has $40 in her lunch account and pays $2 each day to eat lunch.  Which equation can be used to find the amount of money Sonya has left on her account after x days?

• y = 40 + 2x

• y = 40 - 2x

• y = 2 + 40x

• y = 2 - 40x

For lunch, Amanda had a hamburger and some potato chips. The hamburger totaled 325 calories and each chip had 12 calories. Write a liner equation to represent the situation.

• y = 12 + 325

• y = 12x  + 325

• y = 325 - 12x

• y = 325x + 12

The local service center advertises that it charges a flat fee of $50 plus $8 per mile to tow a vehicle. Write an equation that represents the total cost (C) of a service for m miles of towing.

• y = 8x + 50

• C = 50m +8

• y = 50x + 8

• C = 8m + 50

A holiday meal costs $12.50 a person plus a delivery fee of $30. Which equation represents the amount a holiday meal costs, including delivery, for x people?

• y = 12.5x + 30

• y = 12.5 + 30

• y = 12.5 + 30x

A fitness club opens with 80 members. Each month the membership increases by 15 members. Which equation represents the relationship between the number of months the club has been opened, x, and the total fitness club membership, y?

• y=15x

• y=15x+80

• y=x+15

• y=80x+15

Bob has $150 in his savings account and saves $40 per month.

• y=150 + 40

• y=40x + 150

• y=150x + 40

Sonya has $40 in her lunch account and pays $2 each day to eat lunch. Which equation can be used to find the amount of money Sonya has left on her account after x days?

• y = 40 + 2x

• y = - 2x + 40

• y = 2 + 40x

• y = 2 - 40x