#### Answer

See attached graphs:

#### Work Step by Step

Graph the points for each problem and you will notice that the points form a type of line:
a) The line is increasing, as the x- and y-values are directly proportional to each other. This means that the slope is positive.
b) The line is decreasing, as the x- and y- values are inversely proportional to each other. This means that the slope is negative.
c) The line is vertical which creates an undefined slope.