1. 6.0
Sorry, this problem is really hard to explain, I just flipped the triangle and used logic.
2. A
This is because they share one vartical angle, and 2 sides are proportional to each other with a 2:1 ratio.
3. 12
2x+10 = 3x+3
10-3 = x
7=x
Plug it in:
7+5 = 12