One just does not just pick a price and stick it to a product. There is almost a science to deciding what to charge. There is the figure for labor, the products to make the final item, overhead, taxes, electricity and everything else under the sun. It is also difficult to maintain inventory without the chance of it being ripped off or spoiling, in the case of food service. One needs to take into consideration of the peak seasons and the times that are not that great for business.
Advertising needs to be budgeted in for the service as well.
It is understandable how come college forcing the students to take so much math for a degree in business. You can not relay on an accountant to make these decision for you. It would not do your business any good to provide a service that is already done if you don't make it own. Give it your personality. What would it be like if all the fast food services serves the same thing and have every little detail down to be exactly a like.