Say that you're thinking of number 
You multiply it by 8, and have 
You add -1 (i.e., you subtract 1) and have 
This equals -17, so you have

Add 1 to both sides

Divide both sides by 8:

So, you were thinking of -2.
If this is graphing you have to graph it first to find the area.
Sounds like 18 servings to me.
6 quarters go into 1.5
6 x 3 is 18 so 18 servings.
Answer: The rate of change in the y coordinate is 75. 78 - 3= 75.