the graph below shows the amount of money left in the schools desk fund, f, after d desks have been…

the graph below shows the amount of money left in the schools 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 schools desk fund decrease? $110 $135 $165 $190
Answer
Answer:
C. $165
Explanation:
Step1: Select two points
Select points $(2,480)$ and $(5,150)$.
Step2: Calculate change in money
Change in money $\Delta f=480 - 150=330$.
Step3: Calculate change in number of desks
Change in number of desks $\Delta d=5 - 2 = 3$.
Step4: Find decrease per desk
Decrease per desk $=\frac{\Delta f}{\Delta d}=\frac{330}{3}=165$.