Answer:

Step-by-step explanation:
1. Subtract 3x from both sides
3x-8y-3x=24-3x
2. Simplify
-8y=24-3x
3. Divide both sides by -8

4. Simply again to get answer.
X^3 +3x^2 +5x +3 / x+1 = x^2 +2x +3
x^3 +x^2
------------
0 2x^2 +5x
2x^2 +2x
----------------
0 3x +3
3x +3
---------
0 0
so the 3rd choice is right sure
All the steps arranged in the attachment!