Let the angles of the quadrilateral be 2x, 3x, 5x and 8x. Since, the sum of the angles of a quadrilateral is 360° Then, 2x+3x+5x+8x=360∘ 18x=360° x=20° Then, the angles of quadrilateral are, 2x=2x×20°=40° 3x=3×20°=60° 5x=5×20°=100° 8x=8×20°=160° Largest angle is 160° and smallest angle is 40° Now the supplement angle of 160°=180°–160°=20° And complement angle of 40°=90°–40°=50°. Hence, the sum of supplement of largest angle and complement of smallest angle of quadrilateral is=20°+50°=70°.