Answer:
Average cost per year = 400 + 180/x
Explanation:
Using the formula y=mx+b
We know that b is the y intercept or initial value. That would be the start up costs
m is the slope on costs each time x increases, that would be 400 per year
Costs = 400x + 180
To find the average cost per year, we need to divide by x
Average cost per year = (400x + 180)/x
= 400 + 180/x