$\text{The slope of the line joining the points } (x_1,y_1) \text{ and } (x_2,y_2) \text{ is given by } m=\dfrac{y_2-y_1}{x_2-x_1}$.So, the slope of the line joining the points \(\left(-9,5\right)\) and \(\left(3,-10\right)\) is \(\dfrac{\left(-10\right)-\left(5\right)}{\left(3\right)-\left(-9\right)}\) = \(\dfrac{-10-5}{3+9}\) = \(\dfrac{-15}{12}\) = \(-\dfrac{5}{4}\)The slope is negative, so the line is falling from left to right.