Hello, Guest!~
I'm going to elaborate on Electric Pavlov's excellent answer.
So, basically, the Law of Sines says that, according to Khanacademy, a side labeled, "A" over the sine * opposite of it, which is, angle "a", is equal to a side labeled, "B", over the sine * opposite of that side, which is the angle "b".
In short, you end up with, \(\frac{Side\ A}{Angle\ a}=\frac{Side\ B}{Angle\ b}\), and you can add the third side the same way: \(\frac{Side\ A}{Angle\ a}=\frac{Side\ B}{Angle\ b}=\frac{Side\ C}{Angle\ c}\)
For your case, we get:
\(\frac{sin(70)}{5.7}=\frac{x}{5} \\ \\ sin(x)*5.7=sin(70)*5 \\ \\sin(x)=\frac{5sin(70)}{5.7} \\ \\x=sin^{-1}(\frac{5sin(70)}{5.7})\)
I do hope the math is correct.
From here, you can just plug it in!
I hope you did take away something from my answer!
-TheLovely1