The values are as follows:
18. m∠1 = 104°
19. m∠2 = 79°
20. m∠3 = 65°
21. m∠5 = 73°
The explanation for the questions 18-21:
18. m∠1 = 104°
Given: m∠1 = 104°
Reason: m∠1 is the measure of angle 1.
19. m∠2 = 79°
Given: m∠2 = 79°
Reason: m∠2 is the measure of angle 2.
20. m∠3 = 65°
Given: m∠3 = 65°
Reason: m∠3 is the measure of angle 3.
21. m∠5 = 73°
Given: m∠5 = 73°
Reason: m∠5 is the measure of angle 5.