Stores will advertise that there is a discount on an item to attract buyers. do you think that advertised discounts are always the best deal? why or why not? what is a real-world scenario in which the discount is not the best price? pl

The perimeter of ? cde is 55 cm. a rhombus dmfn is inscribed in this triangle so that vertices m, f, and n lie on the sides cd , ce , and de respectively. find cd and de if cf=8 cm and ef=12 cm. the answer is not cd=20 and de=15. i have tried that one, it does not work.