Is d=2t proportional or non preportional ?

If i have 20$ and i gave 5$ away how much i got

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.

Stefan's sculpture is 7/12 foot tall. he attaches it to a base that is 1/3 foot tall. how tall, in feet, is the sculpture with the base?