12:
x = 8
D = 38
E = 75
F = 67
13:
x = 13
Q = 30
P = 126
R = 24
Step-by-step explanation:
To get x, the formula is a+b+c=180°
a, b, and c being the angle's.
The photo below shows the process of them being solved.
Hope this helps!
Let me know if you need anything else :)