Opposite angles in a parallelogram are congruent, so 3x+40 = x+50 and x = 5. That means that those 2 angles measure 3(5)+40 = 55, and the other 2 angles, which are congruent to each other, add up with the other to equal 360. 360-55-55=250. Divide that between the other 2 remaining angles to get that those angles each measure 125.
