I call this a "purchase" problem, because I know of no other name. The example below was presented to me a long time ago. To prevent everyone trying the example, the combination of the prices 15, 17 and 22 will be rejected.
Do not worry, the solution for this example is at the bottom of this page. Although, it would have been a nice exercise for you.
The "purchase" problem to be solved:
There are three articles, each with a different price. One has to buy a given total number of articles for a given amount of money.
Question:
How many of each of the articles should be bought?
So if you have a similar problem, just change the default values and "solve" it.
If you are sure, you do not want to solve the example yourself, click here.
If you have any remarks or questions, you can always contact me.