5 help please and thanks

What is the answer to |-2x-5|-|-4+8| and x=7

Solve the system of equations. y= 2x y= x^2 - 15

Find the exact value of each of the following. in each case, show your work and explain the steps you take to find the value. (a) sin 17π/6 (b) tan 13π/4 (c) sec 11π/3