Writing and Graphing Equations in Two Variables

The graph below shows the amount of money left in the school's desk fund, f, after d desks have been purchased. For each new desk that is purchased, by how much does the amount of money left in the school's desk fund decrease?

$110

Which graph represents viable values for y = 2x, where x is the number of pounds of rice scooped and purchased from a bulk bin at the grocery store and y is the total cost of the rice?

A

Which graph represents viable values for y = 5.5x, where x is the number of cans of tomato paste and y is the total weight of the sealed cans in ounces?

B

Which graph shows the equation V = 4 + 2t, where V is the total volume of water in a bucket and t is the elapsed time in minutes?

C

Which description is represented by a discrete graph?

Kiley bought a platter for $19 and several matching bowls that were $8 each. What is the total cost before tax?

Jayne stopped to get gas before going on a road trip. The tank already had 4 gallons of gas in it. Which best describes why the graph relating the total amount of gasoline in the tank, y, to the number of gallons that she added to it, x, will be continuous or discrete?

The graph will be continuous because the amount of gas that she added to the tank does not need to be an integer amount.

A store sells notebooks for $3 each and does not charge sales tax. If x represents the number of notebooks Adele buys and y represents the total cost of the notebooks she buys, which best describes the values of x and y?

The value of x can be any integer greater than or equal to 0, and y will be an integer greater than or equal to 0.

Peaches are being sold for $2 per pound. If x represents the number of pounds of peaches bought and y represents the total cost of the peaches, which best describes the values of x and y?

The values of both x and y will be real numbers greater than or equal to 0.

Julie needs to cut 4 pieces of yarn, each with the same length, and a piece of yarn 7.75 inches long. Let y represent the length of each of the equal pieces of yarn that Julie decides to cut. What is the equation that can be used to determine the total length of all of the yarn that she ends up cutting, t? Is the graph of the equation continuous or discrete?

t=4y+7.75; continuous

Otto used 6 cups of whole wheat flour and x cups of white flour in the recipe. What is the equation that can be used to find the value of y, the total amount of flour that Otto used in the recipe, and what are the constraints on the values of x and y?

y=x+6; x is any real number greater than or equal to 0, and y is any real number greater than or equal to 6.