Explanation:
Given
It is a parallelogram so opposite angles of parallelogram are equal
1st and 3rd angle = 9°
2nd and 4th angles = x
Now
9° + 9° + x + x = 360°< being sum of angles of parallelogram >
18° + 2x = 360°
2x = 360° - 18°
2x = 342°
Therefore x = 171°
Now
measures of all other angles
9° , 171° , 9° and 171°