Explanation: 1- getting the value of x: We are given that the two sides (x-4) and (11) are equal. This means that: x - 4 = 11 x = 11 + 4 x = 15 2- getting the value of y: For any polygon, the sum of measures of its angles is equal to (n-2)*180 where n is the number of sides. The given is a trapezoid, therefore, it has n - 4 sum of its interior angles = (4-2)*180 = 360 We are given that each two opposite angles are equal. Therefore: 360 = 2 (4y - 20) + 2y 360/2 = 4y - 20 + y 180 = 5y - 28 200 = 5y y = 200/5 y = 40
