I'm confused on where to start. Can someone help break it down. That would be so helpful.

1.) an athlete executing a long jump leaves the ground at a 30° angle and travels 7.80 m. What was the takeoff speed? If this speed were increased by just 5.0 Percent, how much longer would the jump be?

vertical problem:

s = muzzle velocity

Vi = s sin 30 = s/2
u = s cos 30 = .866 s

7.8 = .866 s t
where t is time in the air
so
s t = 9
t = 9/s

h = Hi + Vi t -4.9 t^2
at ground h = Hi = 0
0 = 0 + (9)/2) - 4.9 (81/s^2)
4.5 = 396.9/s^2
s = 9.39 m/s

Now you do all that for
new s = 1.05 s = 9.86 m/s