Hi, i need with these questions!

8. factor 54a+24b.

(that's all it says, if you need the multiple choice answers, ill comment them)

9. which of the following expressions is equivalent to 6(5+3x)?

(if you need multiple choice answers ill comment)

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.