Simplify the following expression. 7^-5/6x7^-7/6

Rationalize the denominator- 12x/√x-10

Prove that 16^4-2^13-4^5 is divisible by 11.

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.