This is a trig question, so you would need a proper calculator.
Remember SOHCAHTOA
Sine- opposite/hypotenuse
Cosine- adjacent/hypotenuse
Tangent- opposite/adjacent
For this question, you would use Tan because looking at the angle of 60°, the x is adjacent and the 4√6 is opposite.
the equation would look like:
Tan60 = 4√6 / x
4√6 / 60 Tan =
x = 8.5