Cell phone Company ABC charges a $12 start-up fee plus $0.08 per minute, x/ Cell phone Company WYZ charges $0.20 per minute, x, with no start-up fee. Which function represents the difference in cost between Company ABC and Company WYZ?

The slope of f(x) is 10 and the slope of g(x) is 5; g(x) has the greater y-intercept.

To find the slope of f(x), we use the slope formula:  m=(y₂-y₁)/(x₂-x₁) = (-1--11)/(0--1) = (-1+11)/(0+1) = 10/1 = 10.

To find the slope of g(x), we just look at the form it is in.  It is written in slope-intercept form, y=mx+b, where m is the slope.  The number in g(x) that would correspond to m is 5.

The y-intercept of f(x) is found by looking at the points.  Any y-intercept will have an x-coordinate of 0; the only point like this in the table is (0, -1) so the y-intercept is -1.

For g(x), we again look at the form y=mx+b.  The number that corresponds with b is the y-intercept; in this case, it is 1.  1>-1, so g(x) has the larger y-intercept.