Area of a rectangle is length times width:
(2x-9) * (x+5) = Area FOIL this!
2x^2 + 10x - 9x - 45 = area
2x^2 + x - 45 = area
When given this type of problem, the only way to get an answer is to be given some more information about the shape or the area. Since we aren't given any other relationship between width and length, our answer is an equation.