Question

The width and area of the rectangle are shown. what is the length of the rectangle?

Answer 1

A = L x W

Can you type out the expressions here? A is area and W is width, and L will stay unknown.

Answer 2

A=L+W
(4b^3 + 5b - 3)in^2 = L + (2b - 1)in

Answer 3

+ means 'add'
x or * means multibly

You cannot get area by adding the sides. (Adding the sides gives you perimeter, and that is something different)

Here is an area example to help you get on track:

So your equations should be:
A=L x W

(4b^3 + 5b - 3) in^2 = L x (2b - 1) in

Good so far?