The function C(x)=−5x+625 represents the cost to produce x items. What is the least number of items that can be produced so that the average cost is no more than $20?

Answer 1

A function is like a machine that no matter what you put into it, the function does the same thing with it. So, no matter what we put into this function it will be multiplied by -5 and 625 will be added to it.

You are told what price you want the function to pop out, in this case $20. So, $20 is the answer and x is still unknown:

20 = -5x + 625

Now solve using algebra:

20 = -5x + 625

-605 = -5X

121 = x