
1) x=9, because we can use the Pythagorean theorem, x^2 + 144 = 225, x^2 = 81
2)
, because 6^2 +6^2 = 72, 
3)
, because 
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You need to be more specific about this question
What do you mean by supply and demand? you want me to explain what supply and demand is?
Known Variables:
Δy = 1.5 m
v0 = 30m/s at 60° above the horizontal.
t = 4.0 s
a. vfy = v0y + at
0 = 30sin(60) + (-9.8)t
-25.98 = -9.8t
t = 2.65.
4-2.65 = 1.35s.
Δy = v0yt + at^2/2
Δy = 25.98(2.65) + (-9.8)(2.65)^2/2
Δy = 34.44 m
1.5 + 34.44 = 35.94 m.
Δy = v0t + at^2/2
Δy = (-9.8)(1.35)^2/2
Δy = -8.93.
35.94 - 8.93 = 27.01 m.
b. vfy = v0y + at
0 = 30sin(60) + (-9.8)t
-25.98 = -9.8t
t = 2.65.
Δy = v0yt + at^2/2
Δy = 25.98(2.65) + (-9.8)(2.65)^2/2
Δy = 34.44 m
1.5 + 34.44 = 35.94 m.
vfy = v0y + at
vfy = (-9.8)(1.35)
vfy = -13.23 m/s.
I might have gone wrong somewhere so please check my answer! Cheers!