Step-by-step explanation: The slope of a line that is perpendicular will always be the opposite ( change positive to negative) and the inverse. Since 1/3 is the slope we would change it to negative (-1/3) and flip it. The slope of the new line is -3. Your new equation is y=-3x+b. Now, plug in 4 for x and -5 for y. -5=-3(4)+b. B=7.
