Work Step by Step
In the equation $y=mx+b$, $m$ is the slope and $b$ is the y-intercept. Since the slope is $-3$, the equation becomes $y=-3x+b$. Now, we substitute the point (1,-5) in the equation to find the intercept b: $y=-3x+b$ $-5=-3(1)+b$ $-5=-3+b$ $-5+3=b$ $b=-2$. Therefore, the equation of the line is $y=-3x-2$.