Answer:
Step-by-step explanation:
Angle 3 is supplementary to 57, so they add up to equal 180. Therefore, 180 - 57 = angle 3, which is 123. Before we can find angle 4 we need angle 2. Anglee 2 and 72 are complementary, so they add up to equal 90. Therefore, 90 - 72 = angle 2, which is 18.
Angle 2, 3, and 4 all add up to equal 180 according to the Triangle Angle-Sum Theorem, so
18 + 123 + angle 4 = 180 and
141 + angle 4 = 180 so
angle 4 = 39
