The cosine of 30° is √3 / 2.
Since cosine is Adjacent over Hypotenuse, Hypotenuse = (2 / √3) * 9 = 18 / √3.
The cosine of 45° is √2 / 2.
Therefore, X = (2 / √2) * (18 / √3) = 36 / √6 = 18 / √1.5 = C
I think I know how to do it
Your equation is:
P₁V₁ = P₂V₂
You Know:
Initial:
P₁ = 84 Pa
V₁ = 336 L
New:
P₂ = ?
V₂ = 216L
Plug this into the equation:
P₁V₁ = P₂V₂
(84 Pa)(336 L) = P₂(216 L) Divide 216 on both sides

130.6666666 = P₂
(if your doing significant figures, you have 2 sig figs)
130 Pa = P₂
I think it might be the last one. Hope it helps:)