Can someone explain how to do c i you

So imagine these are all things so u have
3pencils
4rulers
7erasers I say rubber cause I’m British
1 pencil
8 rulers
And 1 rubber

X and xsquared are two different things so you cant add them or subtract
And single numbers two

So add 3x squared to x squared (or 1 xsquared same thing) u get 4x squared

Then u minus 8x from 4x and get -4x
Then you subtract -7 from -1 and get -8
Then you write them together like 4x squared + -4x -8

There if u need any more help I’m open