Modeling Linear Functions

Which equation represents the total cost of a repair by an electrician after x hours?
An electrician charges $90 per hour plus a $50 travelling fee.

• y = 50 - 90x

• y = 90x + 50

• y = -50x + 90

• y = -90 - 50x

The start up cost to join eTunes music is $7.95 plus $0.95 per song downloaded.  Write a linear equation that could be used to find how many songs he downloaded.

• y = 0.95x + 7.95

• y = 7.95x + 0.95

• y = 0.95x - 7.95

• y = - 0.95x + 7.95

A driving range charges $4 to rent a golf club plus $2.75 for every bucket of golf balls you hit. Write an equation that shows the total cost c of hitting b buckets of golf balls.

• c = 2.75b + 4

• c = 2.75b

• c =  4b- 2.75

• c = 2.75b - 4

d=125 + 80n models the amount of money (d) in the register after selling n tickets. How much money does she have in the register before selling any tickets? 

• $125

• $80

• $205

• $45

Penelope is going to the carnival to ride the rides. It costs $20 to get into the carnival and ride tickets are $0.50 each. Write an equation that represents this scenario if she spends $35 in all.

• .50x + 20 = 35

• .50x = 35

• .50 + 20x = 35 

• .50x - 20 = 35

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

Talk time Phone Company charges $0.12 per minute of phone use plus a monthly service fee of $8.00 for its phone service.  Which equation below can be used to find c, the total cost for one month when m, minutes are used?

• c = 0.12m + 8m

• c = 8m + 0.12m

• c = 0.12m + 8

• c = 0.20m

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

Lee charges $3 for a basket and $2.50 for each pound of fruit picked at the orchard. Write an equation in y = mx + b form for the total cost of x pounds of fruit from the orchard.

• y = 3x + 2.5

• y = 2.50x + 3

• y = 2.50x 

• y = 3x + 2.50

You plan to go snowboarding. The resort charges $15 an hour in addition to $25 to rent a board. Write an equation that represents the cost to go snowboarding for the day.

• y=15x-25

• 15x+25y=100

• 25x+y=15

• y=15x+25