Step-by-step explanation:
step 1. AD is parallel to BC
step 2. <y = 90° (definition of right trapezoid)
step 3. x + y + 90 + 140 = 360 (a quadrilateral has 360° of internal angles)
step 4. x + 90 + 90 + 140 = 360
step 5. x = 40°.
