The shape of the graph is similar to the letter W; however, the region of interest will lie on the right of the origin, which means only the right half of the W(a negative number of cans cannot be produced). The profit produced will be maximized if the number of cans produced is greater than 3. The company will be at a loss if the number of cans produced is near 2.5. The break even situations are present if the company produces 2 or 3 cans.
If

then we have

By Fermat's little theorem, if

is not divisible by a prime

, then

This works for

; in this case, we would have