Rate of change and initial value from scenarios and graphs

If chocolate chip cookies cost $3.00 per cookie plus $2 for boxing them up in a decorated box, what would the equation be for this relationship if x is the number of cookies and y is the total cost?

• y= 3 + 2x

• y= 3x + 2

• y= 3x + 2x

• y= 5x

A plumber charges $50 to make a house call plus $40 for each hour worked. What is the equation that represent this relationship if x is the number of hours worked and y is the to total cost?

• y= 50x + 40

• y= 50x + 40x

• y= 40x + 50

• y= 90x

Scott's Automotive charges a $35 fee to see your car plus $7 per hour to work on it. Write an equation that represents this scenario.

• y= 35x + 7

• y= 7x

• y= 7x - 35

• y= 7x + 35

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 = 12.50x + 30

• y = 12.50 + 30

• 12.50x = 30

For babysitting, Nicole charges a flat fee of $3, plus $5 per hour. What information is given and what equation should you use?

• A slope and a y - intercept is given; use y = mx + b.

• A slope and a y - intercept is given; use y - y1 = m(x - x1).

• Two points are given; use y - y1 = m(x - x1).

• Two different items that add to a total are given; Ax + By = C

Suppose that a bike rents for $4 plus $1.50 per hour. Write an equation in slope-intercept form that models this situation.

• y = 4x + 1.50

• y = 1.50x + 4

• y = -4x +1.50

• y = 4x - 1.50

An airplane 30,000 feet above the ground begins descending at a rate of 2,000 feet per minute. Write an equation to model the situation.

• y = - 2,000x + 30,000

• y = - 2,000x - 30,000

• y = 30,000x + 2,000

• y = -30,000x + 2,000

What does "m" represent in y=mx+b?

• y-intercept
• slope
• macaroni
• nothing

A strong cold front blew through during the night.  The temperature outside began to drop rapidly.  The graph shows the temperature at each hour after the cold front blew through.  What is the rate of change of the graph?

• 2.5°F per hour
• 0.2°F per hour
• -0.2°F per hour
• -2.5°F per hour

What is the rate of change for the following graph?

• 80
• 20
• 40
• 160