The 40 percent is equal to the quotient of 40 and 100.
B
Use the function obtained in Part A to calculate the discount.
A
Function: y=0.4x Graph:
B
51 dollars
Practice makes perfect
Consider that a furniture store is having a sale where everything is 40 percent off. To find the amount of discount on an item at regular price, we need to multiply the price by the quotient of 40 and 100.
y=40/100x → y=0.4x
Here, y represents the amount of discount and x is the regular price of the item. We want to graph this function. To do so, we will construct a value that shows the amount of discount for different regular prices.
x
y=0.4x
y
20
y=0.4( 20)
8
50
y=0.4( 50)
20
80
y=0.4( 80)
32
These points lie on a line. The value of x and its corresponding value of y represent a ordered pair that can be plotted in a coordinate plane. Let's plot the ordered pairs and draw a line through the points.
We want to find the sale price of a bookshelf that has a regular price of 85 dollars. To do so, we will use the function obtained in Part A.
y=0.4xLet's substitute x= 85 into the function and calculate the discount.
The amount of discount is 34 dollars. Now that we have the discount we can subtract it from the regular price to obtain the sale price of the bookshelf.
85-34=51 dollars
The sale price is 51 dollars.
