We know that if two angles form a line, the sum of the angles is 180 degrees. So, 2x-3+7x+21=180.
Combining like terms, we get 9x+18=180.
Subtracting 18 from each side, we get 9x=162.
Dividing by 9, we get x=18.
So, angle KMX is 2x-3=2(18)-3=33.
The compliment of an angle is the angle that is needed in order to make a right angle with the sum of the angles.
So, the compliment of 33 degrees is 57, as 33+57=90.
