Answer:
12
Step-by-step explanation:
Answer:
The answer to your question is x = 6
Step-by-step explanation:
To solve this problem use proportions. Just look for the right sides so the proportion be correct.
Sides of the small triangle = Sides of the big triangle

Solve for x

Simplification
x = 
Result
x = 6
Ok, so you already know that mQBO = 3x-15°
You just need to find x.
You use mSAO and mQAO to solve for x. You can also see that triangle AOS and triangle AQO are similar. Solve these two equations for x and mAOQ:
90+(2x+6)+mAOQ = 180
90+(4x-12)+mAOS = 180
x=9 and mAOQ=mAOS=66°
Now you can find mQBO, by simple algebra:
3x-15=3*9-15=12
So, mQBO is12 degrees.