a whole circle is equal to 360 degrees so if 52 +90= 142 the opposite side also equals 142 because they are clearly the same size. ED and AB are also the same sizes. if 360- (142+142) = 284. then you will have to divide 284 by 2. so 284÷2=76 and 76÷2=38°
hope you understand, I not that good at explaining things
