Since a straight line is 180 degrees, ∠ACD and ∠ACB add up to 180 degrees. Therefore, ∠ACB=180-∠ACD=180-5x-5=175-5x. As the angles in a triangle add up to 180 degrees, ∠A+∠B+∠ACB=x+2x+15+175-5x=180=-2x+190. Subtracting 190 from both sides, we get -10=-2x. Next, we can divide both sides by -2 to get x=5 and plugging that into 2x+15=∠B, ∠B=2*5+15=25
