I need help with question number 3

Hey there! I'd be delighted to help you out!

First, let's write down our expression!

When we look at this expression, we see that all of the numbers are terms, or numbers that are added. We have four terms in this equation, which are:

Now, to simplify, we want to combine like terms. Like terms are numbers that have the same variable (or no variable) and are raised to the same power. 1 and 5 are like terms because they both have no variable and they are both raised to the power of 1 (any number that is itself is raised to this power). 4x and 12x are like terms because they both have an x and a power of 1. 4y and 5x are not like terms because they have different variables. 4x³ and 2x² are not like terms because they are raised to different powers.

Now, we see that  with our numbers, x² and -2x² are like terms, and -x and 8x are also like terms. We can combine accordingly.

Now we combine to get our simplified expression!

I hope that this helps! Have a wonderful day!

1/800 is the right answer