start by converting 100 mph into ft/s to get in correct units
... sub in your known values
(b) do what it says ... graph the parametric equations in your calculator. since the fence is 400 ft away in the x-direction, solve the equation for t
then use that value of t to find the y-position ... if it's greater than 10 ft, homerun.
(c) here's where you can use your graphing calculator to play with the angle to ATQ.