What is the missing statement in step 3 of the proof?
om21 = m 22
om21+ m 22 = 90°
omz2 = m23
om 22 + m 23 = 180°

White shapes and black shapes are used in a game. some of the shapes are circles. while the rest are squares. the ratio of the number of white shapes to the number of black shapes is 5: 11. the ratio of the number of white cicrles to the number of white squares is 3: 7. the ratio of the number of black circles to the number of black squres is 3: 8. work out what fraction of all the shapes are circles.