Let's start with the first part of the problem. There are 25 self-portraits that are planned to be sold at $2.75 each. If that's the case, how much money are they expecting to make (assuming they sell all 25 self-portraits)?
This is:
Once we have found that, now the task is to find out how they can still make that much money with three of the self-portraits now ruined, and only 21 self-portraits left.
If we need to get $68.75 to pay for the materials and we only have 21 self-portraits to sell, we could divide:
Therefore, the new minimum price we need to set for the remaining self-portraits in order to pay for the materials is $3.27 approximately.