Original price - $82. percent of sale price - $65.60

To determine a percentage difference, simply divide the difference of the two numbers by the original. For instance, 82-65.60=16.4 16.4 is 20% of 82, so the discount is 20% (16.4/82)

Abit confused about what you mean, but i think you might be referring to slope intercept form: y = mx + bin that case b, or the y intercept is already given.(0,-1)find the slope by using the formulay2 - y1/x2 - x1the final slope will be 4/2, equivalent to 2.now your equation should look like thisy = 4/2x -1sorry if this didn’t you out!