9514 1404 393
Answer:
51°
Step-by-step explanation:
The two marked angles are a linear pair, so supplementary.
(3x +15) +(10x +9) = 180
13x = 156 . . . . . . subtract 24
156/13 = x = 12 . . . . divide by 13
The smaller angle is ...
3x +15 = 3(12) +15 = 51
The angle with the basement floor is 51°.
