Asa can someone do number 4 for me

Remark
Each term inside the brackets must be divided by 2x. Your result will look like this



Everything is well behaved except the last term. 
Your answer is
2x^2 + x - 

What you do next depends on what your choices are.
2x^2 + x - (5/2x) is one way to right it.
2x^1 + x - 2.5 / x is another way. This one really does depend on what your teacher wants. If you have a real person making this, any one of the choices will do.

It would be 18 cm