Answer: x=5
Explanation: 
sin=opposite side/hypotenuse
The opposite side is x and the hypotenuse is 10. 
So your equation is: sin(30)=x/10 
In order to get x by it self times ten to each side of the equation. 
10 x sin(30)= x
Put 10 x sin(30) into graphing calculator and make sure your calculator is set to degrees. 
Your answer: 
5= x 
Work on paper: