Equations from Scenarios

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 = 15 + 0.20x

• C =15 (0.20x)

• C = 15 + x + 0.20

• C = 0.20 + 15x

At Joe's Clown Car Rental Agency, renting a car costs $35 plus $0.75 for every mile it is driven.  What is an equation that can be used to find the number of miles, m, a vehicle was driven, if the total rental charge was $222.50?

• 222.5 = m(35 + 0.75)

• 222.5 = 35 + 0.75m

• 222.5 = 0.75 + 35m

• 222.5 = 0.75(m + 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

Which of the following situations could be descried by the equation y= -25x + 120

• There are 120 people in the football stadium, and 25 more are entering each hour.

• A plumber charges $25 for a house call and $120 per hour.

• A teacher has 120 students. Her third period has 25 students

• There are 120 gallons of water in a tank. It releases water at a rate of 25 gallons per minute

Speedy Boat Rental charges a $15 deposit fee plus $2 for each hour of use to rent a paddle boat.  Write an equation for C, the total cost, to rent the boat for h hours.

• h = 2C + 15

• C = 15h + 2

• h = 15C + 2

• C = 2h + 15

Bob's Plumbing charges $15 per hour plus a service fee of $40 for coming out to your house. Which equation models this situation?

• y = 15x + 40

• y = 40x + 15

• y = 15x

• y = 15x - 40

Scott's Automotive charges $35 for each car plus $7 per hour. Write an equation that represents this scenario if Kylie was charged $63.

• 35x + 7 = 63

• 7x = 63

• 7x - 35 = 63

• 7x + 35 = 63

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

• y = 12.50 + 30x

• y = 30 + 12.50x

• y = 12.50 + 30

• 12.50x = 30

Researchers in Antarctica discovered a warm sea current under a glacier that is causing the glacier to melt. The ice shelf of the glacier had a thickness of approximately 450 m when it was first discovered. The thickness of the ice shelf is decreasing at an average rate of 0.06 m per day. Which function can be used to find the thickness of the ice shelf in meters x days since the discovery?

• t(x) = 450 - 0.06x

• t(x) = -0.06(x + 450)

• t(x) = 450 + 0.06x

• t(x) = 0.06(x + 450)

At a restaurant jars of tomato sauce are stored in boxes in the pantry. Each box contains 8 jars of tomato sauce. A cook uses 2 jars from 1 of the boxes. Which function shows the relationship between y, the total number of jars of tomato sauce remaining in the pantry, and x, the number of boxes in the pantry?

• y= 8x + 6

• y = 8x

• y = 8x - 2

• y = 6x