Answer:
40
Step-by-step explanation:
Two ways we can solve this problem:
1. Graphically
2. Mathematically
Because you already solved it graphically, I will show you how to do so mathematically. Of course, graphically is much much easier and more efficient in this problem.
Let's break the problem down.
First, we are given a graph which contains a slope.
To find slope, we use the technique -> rise/run
Picking 2 obvious points from the graph, we can see
1st point -> (10, 20)
2nd point -> (40, 80)
Now, let's find the slope

Now, we have an equation y = 2x, where y = number of pies and x = cups of sugar
We want to find how many cups of sugar we need to bake 80 pies. Simply substitute 80 = number of pies = y
y = 2x -> 80 = 2x
Solving for x, divide both sides by 2
40 = x
We need 40 cups of sugar.
At this case it could be calculated like this: 7+5*20=107
Find the x and y intercepts or any other 2 points. (I advise you finding the y intercept though.)
then calculate for slope using:
y(2) - y(1)
________
x(2) - x(1)
The (2) and (1) are not exponents they are small numbers at the bottom of the numbers.
The slope is: 4