Answer:The Question is Incomplete still What i understood I let you Explain.x = 78° Step-by-step explanation:Let m∠ A = 78°m∠ B = 56°m∠ C = 100°m∠ D = (x + 48)°Be angles of Quadrilateral.To Find:x = ?Solution:Property of a Quadrilateral sum of the measures of the angle is 360°.∴ m∠ A + m∠ B + m∠ C + m∠ D = 360°Substituting above given values we get∴ 78° +56° + 100° + ( x + 48° ) = 360°∴ x + 282° = 360°∴ x = 360° - 282°∴ x = 78° ........... which the required answer