This is because angle 1 and the angle with 27 degrees are opposite angles and angle 4 because it is a corresponding angle, and because of angle 4 angle 7 because angles 4 and 7 are opposite diagonal angles
You can multiply by 12 because to get rid of the fractions all terms should be divided by the LCM (ie the smallest multiple that is exactly divisible by 2, 4 and 3)
Multiples of 3 = 3, 6, 9, 12
Multiples of 4 = 4, 8, 12, 16
Multiples of 2 = 2, 4, 6, 8, 10, 12
Therefore the fractions should be multiplied by 12
