Find equation where line passes through (7,8) and perpendicular to line y=8

Since in y=8, the slope is 0 (because there is no x) and b is 8 in y=mx+b, we know that the perpendicular line is x=(something) because the perpendicular lines of y=<number> are x=<number> due to that y=<number> equations are strictly horizontal while x=<number> equations are strictly vertical. Since we know that x=<number> has to pass through (7, 8), x =7

The answer is option c.

the formula of a slope:

from a table we have

substitute:

the slope of f(x) is -1.

the graph of funcfion g(x) is a horizontal line. the slope of a horizontal line is equal 0. therefore the slope of g(x) is 0.

-1 < 0

answer: the function g(x) has the greatest slope.