$\text{The slope of the line joining the points } (x_1,y_1) \text{ and } (x_2,y_2) \text{ is given by } m=\dfrac{y_2-y_1}{x_2-x_1}$.So, the slope of the line joining the points \(\left(9,-10\right)\) and \(\left(-7,10\right)\) is \(\dfrac{\left(10\right)-\left(-10\right)}{\left(-7\right)-\left(9\right)}\) = \(\dfrac{10+10}{-7-9}\) = \(\dfrac{20}{-16}\) = \(-\dfrac{5}{4}\)The slope is negative, so the line is falling from left to right.