You can do part a using The Pythagoras theorem:-
30^2 = x^2 + 24^2
x^2 = 30^2 - 14^2 = (30+24)(30-24) = 324
x = 18
70 miles per hour
5280 feet per mile
5280 x 70 = 369600 feet per hour
3600 seconds per hour
369600 divided by 3600 =
102.67 feet per second (rounded to the nearest hundredth)