by looking at the diagram you can infer that the triangles are similar, this means that angle B and angle C both equal 47 degrees. you can also infer by the straight angle underneath both angles the both angle Ds add up to 180 and because they are similar triangles that means they are right angles giving you the x value, 90 degrees. after this you know that a triangle adds up to equal 180 degrees meaning if you add 90 and 47 together and subtract that from 180 you get the value of y, 43.
