A perpendicular line will have a negative reciprocal slope of the original line. This means the slope will be negative and flipped "upside down" from the original slope.
First, make sure the equation is written in slope-intercept form:
20x-2y=6 can be re-written as: y=10x-3 (solve for y)
Second, find the slope.
The slope of the line is 10 (y=mx+b where m is the slope and b is the y-intercept).
Third, find the negative reciprocal:
The negative reciprocal will be -1/m where m is the slope.
-1/m=-1/10
B is your answer.
