Answer:
<em>The least number of items to produce is 41</em>
Step-by-step explanation:
<u>Average Cost</u>
Given C(x) as the cost function to produce x items. The average cost is:

The cost function is:

And the average cost function is:

We are required to find the least number of items that can be produced so the average cost is less or equal to $21.
We set the inequality:

Multiplying by x:

Note we multiplied by x and did not flip the inequality sign because its value cannot be negative.
Adding 20x:


Swapping sides and changing the sign:

Dividing by 41:

The least number of items to produce is 41
Answer:
x=20
Step-by-step explanation:
x - 5 = 15
x +5 = +5
x = 20