Hello,

you only have to plug in the 19 instead of x in the given equation:

y = 0.85 * 19 + 8 = 16.15 + 8 = $24.15

the factor of x (here it is 20) is called the slope of the line. If x = 0 then the y-value is the y-intercept. Thus you get:

slope = 20

y-interc. = -100