Suppose that the amount of algae in a pond doubles every 4 hours. if the pond initially contains 90 pounds of algae, how much algae will be in the pound after 12 hours? 720 pounds 360 pounds 1,440 pounds 114 pounds

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.