Please help on my hw

Evaluate 4 a for a = 5 2/3 . express your answer in simplest form.

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).

The coordinate grid shows a pentagon. the pentagon is translated 3 units to the right and 5 units up to create a new pentagon. what is the rule for the location of the new pentagon?