What is the slope of the line below

Ary throws a plastic disc to her friend, which her friend catches six seconds after mary throws it. the table shows the height of the disc at one-second intervals. assuming that the throw represents projectile motion, what are the missing values in the table? a = 5, b = 3 a = 4, b = 0 a = 4, b = 3 a = 5, b = 0