Answer:
A= 30
Step-by-step explanation:
This requires several steps.
First, you need to find the 2 other missing angles.
One can be found easily by substracting 130 from 180
so 180-130 = 50
The other angle is the same as 8x+4
Now set up your equation
180=3x-6 + 8x+4 +50
180 = 3x + 8x -6 + 4 +50
180+6-4-50 = 11x
132 = 11x
132/11 = x
12 = x
Now plug in 12 for x in your angle A
A=3x-6
A=3 * 12 - 6
A=36 - 6
A= 30
Answer:2
Step-by-step explanation:
Since this is an arithmetic sequence, you can conclude that
the addition to the number is constant.
Let x = the number asked
k = constant
number added to the sequence
7 + k = x
x + k = 17
Solve the system of equation:
7 + k + k = 17
7 + 2k = 17
2k = 10
k = 5
Therefore, the missing number is 12 (7 + 5).
hence 
