the y - intercept is where the line cuts the y- axis... or vertical axis. this is her height when the observer first sees her
pick 2 points on the line and find the slope
say (0, 4500) and (1, 3000)
slope = change in altitude/change in time
= (3000 - 45000)/(1 - 0)
the x intercept is where the line cuts the x-axis.. horizontal axis
it shows the time it took the skydiver to travel from 4500 feet to the ground.
Hope it helps