Answer
slope = $-2$
Work Step by Step
RECALL:
slope = $\dfrac{y_2-y_1}{x_2-x_1}$ where $(x_1, y_1)$ and $(x_2, y_2)$ are the coordinates of the two points on the line.
Use the points on the line $(1, 6)$ and $(4,0)$ to obtain:
slope = $\dfrac{0-6}{4-1}=\dfrac{-6}{3}=-2$