So, since we have a cubic equation with 4 terms, the first thing we should try is factoring by grouping, so:

Now that we've factored our equation, we can use ZPP and break it up:

So, our solutions are:

Answer:
a. 32.5
Step-by-step explanation:
Remember, in order for this equation to be true either one of the polynomials has to equal 0
So:
-> x+6 = 0
x=-6
-> 2x-5 = 0
2x= 5
x= 5/2
So the answer is x=-6 and x= 5/2.
Hope this helps!
Step-by-step explanation:
2x+8=2x+5
2x-2x=15-8
0x=7