A culture begins with 3000 bacteria and doubles every 15 hours. If the population is increasing exponentially, calculate the population after 30 hours, after 45 hour

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.