Answer:
Its 5
Step-by-step explanation:
A line has to equal 180 so you subtract 105 from 180 to get 75. Then the triangle also has to add up to 180, so if you test it 5 times 9 is 45, and 12 times 5 is 60. if you add 60, 45, and 75 together you get 180. Therefore the answer is 5.
