HELP!! Analysis of the relationship between the fuel economy (mpg) and engine size (liters) for 35 models of cars produces the regression model mpg=36.82−3.857•Engine size. If a car has a 5 liter engine, what does this model suggest the gas mileage would be?

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.