Question

The equation of line t is y = 7/8 x + 2 .Line u is perpendicular to t. What is the slope of line u?

Answer 1

If the slope of a line is m and slope of a line perpendicular to it is m2  the 
m* m2 = -1.

Line t has slope 7/8   therefore line u must have a slope of -8/7.