The opposite angles of a parallelogram are equal. Therefore m∠A = m∠C, so that 5y - 3 = 3y + 27 Subtract 3y from each side. 5y - 3y - 3 = 3y - 3y + 27 2y - 3 = 27 Add 3 to each side. 2y - 3 + 3 = 27 + 3 2y = 30 y = 30/2 = 15
Therefore m∠A = 5*15 - 3 = 72° m∠C = 72°
Let x = m∠B Then x = , m∠B = m∠C Because the sum of the angles in the parallelogram is 360°, therefore x + x + 72 + 72 = 360 2x = 360-144 = 216 x = 216/2 = 108
