Find the slope of the line through each pair of points (-20, -18), (6, -20)

Can someone with this one pre-calc question? the finishing time for a runner completing the 200-meter dash is affected by the tail-wind speed, s. the change, t, in a runner's performance is modeled by the function shown below: t= 0.0119s^2 - 0.308s - 0.0003 predict the change in a runner's finishing time with a wind speed of 3 meters/second. note: a negative answer means the runner finishes with a lower time. round to the nearest hundredth.

If i purchase a product for $79.99 and two accessories for 9.99 and 7.00 how much will i owe after taxes applies 8.75%

How do you find the distance of each number from the mean