Question

You are making candles for your friends, A mold for the candles costs $22.50 and wax to make one candle costs $5. You make 8 candles. How much does that cost?

Answer 1

`color(green)($62.50)` assuming the value of the mold is completely depreciated.

Explanation:

The cost of consumed materials (wax) is
`color(white)("XXX")8xx$5=$40`

If you decide never to make any more candles and can not find anyone willing to by used candle molds from you, the value of the candle molds is effectively reduced to zero.
In this case the cost of making the 8 candles is
`color(white)("XXX")$40+$22.50=$62.50`

If, on the other hand, you plan on continuing to make (perhaps thousands of) candles the depreciation in the cost of the molds may be insignificant.
In this case the only significant cost of making the 8 candles is the cost of the wax
`color(white)("XXX")$40`