First, you can find angle 1 by using the triangle angle formula, stating that all angles add up to 180 deg. Thus, angle 1 is equal to 180-72-57= 51 deg.
Next, you can find angle 2 by using the right angle shown. This means that angle 2 plus 72 deg = 90 deg. Thus, angle 2 is equal to 90-72= 18 deg.
For angle 3, notice that it is bordering the other angle on a straight line. A straight line is equal to 180 deg. This means that angle 3 + 57 deg = 180 deg. Thus, angle 3 is equal to 180-57= 123 deg.
Angle 4 can be found by using the triangle angle formula used for angle 1. In this case, angle 2+3+4 will equal 180 deg. Thus, angle 4 is equal to 180-18-123= 29 deg.
