Question: what is the slope of a line perpendicular to line b?
Answer: First, you should put the equation in slope intercept form (y = mx + b), where m is the slope. The slope of the given line is –10/4. A perpendicular line will have a slope with the opposite reciprocal. In simpler terms, you flip the slope and change the sign, therefore, the opposite reciprocal is 4/10.