The y-intercept which is the (+3) is taken from where the line crosses the y-axis.
The slop is found from rise over run, in this case, -5 to 0 is positive 5 this would go in the denominator, because we go from solid ground 0 to 3 without crossing another solid point, the numerator is 3.
First part is 1:2 because there is 1 hour to every 2 shows. Second part is 3:6 shows because 3 hours is 6 shows. Hope this helps, please rate brainiest answer!