Alright, so what we can take as a given is that arcDE/2= ∠CDE=2x+20 since the arc corresponding to the angle is 2*the angle. To solve for arcDE, we multiply both sides by 2 to get 2(2x+20)=4x+40=arcDE. Since the arcs in a circle add up to 360 degrees and we only have -20+30x and arcDE, we have -20+40+4x+30x=360 using the associative property. Simplifying, we get 20+34x=340. Subtracting 20 from both sides, we get 340=34x. Next, we can divide both sides by 34 to get 10=x.
