He used the property of addition. Hope this helps. Please mark me as brainliest if I am right.
Answer:

Step-by-step explanation:
Angles in a triangle add up to 180°


Angles in a straight line add up to 180°


If you need part A, draw a person and label them 6 feet tall and a shadow coming off of him that is five feet long and draw a basketball hoop that and label it X feet tall and draw a shadow coming from it that is 8 feet long. To solve, you use proportions 6/5=X/8 solving this you get X=9.6 feet which is the height of the rim. Therefore, the rim does not meet regulation height, since the required height (10 feet) is greater than the actual height (9.6 feet).
Easy
82% correct
82 out of 100 correct
82/100 of ttoal correct
total=50
82/100 times 50=
41/50 times 50=41 correct
ratio is 41:50
B is answer