Okay so you can see through the tick marks on the sides of the triangles that they are congruent (equal) triangles so angle AED is the same as angle ABD which gives you 11x-2=6x+13 subtract-6x from each side and add +2 to each side and you get 5x=15 so x=3. Which means that angle ABD=31 degrees. Every triangle’s interior angles added together equal 180 so 31+62-180=angle ACB. So angle ACB=87 degrees. Make senses? Hope this helps.