Suppose Mary decides to make split pea soup. Which result would be a cost?
Mary will give up the chance to eat the minestrone soup, which would have been tastier than the split pea soup. Mary will save some time. The minestrone soup would have taken longer to make than the split pea soup.
Mary is deciding whether to make minestrone soup or split pea soup for dinner. She wants dinner to be as tasty as possible. But she is also hungry and wants to eat soon.
Before you decide to do something, it is often helpful to list costs and benefits.
Costs are what you give up or spend when you decide to do something. Costs involve giving up things that you want or need.
Benefits are what you gain or save when you decide to do something. Benefits involve gaining something that you want or need.
This result is a cost. It involves giving up or spending something that Mary wants or needs:
Mary will give up the chance to eat the minestrone soup, which would have been tastier than the split pea soup.