$\text{The slope of the line joining the points } (x_1,y_1) \text{ and } (x_2,y_2) \text{ is given by } m=\dfrac{y_2-y_1}{x_2-x_1}$.So, the slope of the line joining the points \(\left(10,-9\right)\) and \(\left(-8,-5\right)\) is \(\dfrac{\left(-5\right)-\left(-9\right)}{\left(-8\right)-\left(10\right)}\) = \(\dfrac{-5+9}{-8-10}\) = \(\dfrac{4}{-18}\) = \(-\dfrac{2}{9}\)The slope is negative, so the line is falling from left to right.