Using Sine.
Sine = Opposite / Hypotenuse
sin 60° = a / (6√3) But sin60° = √3/2
√3/2 = a/(6√3)
Cross multiply
2*a = 6√3 * √3
2a = 6 * √(3*3)
2a = 6*3
a = 6*3/2
a = 3*3 = 9
Option E.
Hope this helps.
The answer is option "3, 40".
<span>m∠cab = 2x
m∠acb = x + 30
m∠cbd = 5x − 50
Now,
</span>m∠cab + m∠acb = m∠cbd
2x+x+30 = 5x-50
2x+x-5x = -50-30
-2x = -80
x = 40
X- 3.5 = 5.25
X = 8.75 (Add 3.5 to both sides)
If you'd like further explaining just comment!