Xavier can work no more than 40 hours in a week. he has already worked 24 hours this week. what is the maximum number of 8-hour days can he work for the rest of the week?

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.