Answer:
m∠B = 11°
Explanation:
When two angles are complementary, the sum of the measures equals 90° (the two angles form a right angle together)
Step 1: Therefore, we can find x by making the sum of the measures of angles A and B equal to 90:
m∠A + m∠B = 90
4x - 13 + x - 12 = 90
5x - 26 = 90
5x = 115
x = 23
Step 2: Now, we can plug in 23 for x in the equation representing m∠B:
m∠B = x - 12
m∠B = 23 - 12
m∠B = 11°
Other Examples: There are many ways to have two complementary angles, where none of the two angles are 0 or 90, including (1° + 89°), (2° + 88°) (3° + 87°), ..., (44° + 46°)
Let's say that m∠X = 1° and m∠R = 89°. The two angles are complementary since 1 + 89 = 90°