So area is length*width, we have the area and length which is 5x^2 + 43x - 18 and x + 9. So we need to divide. First the x, what times x is 5x^2? 5x, x*x is x squared. Then we need to apply the 5x to 9. 5x*9 is 45x, and we can’t do anything to the 18 because 18/5 is a decimal. After that we subtract the new area with the old one. 5x^2 + 43x - 18 minus 5x^2 + 45x which is -2x - 18. Now we divide the -18 with 9 which is -2. Remember the 5x we had from using the x? We put that and -2 together which is 5x-2, and that’s your width. Hope this helped!
