2b^2 + 81/2 b + 4
basically 2b^2 + 16b + 49/2 b + 4
= (2b^2) + 16b+49/2b) + (4)
= 2b^2 + 81/2 b + 4
I think it is D but i am not too sure
You need this key result: in any polygon, the sum of the interior angles is

where
is the number of sides of the polygon.
Your polygon has seven sides, and the measures of all angles are given. So, we can write

Again, we've simply written that the sum of all interior angles is the number of sides, minus two, times 180.
We can simplify both sides: we sum like terms on the left hand side, and we easily compute the right hand side:

and we can solve this equation for
by dividing both sides by 30:

Finally, the required angles is 
1: 0.5 and 50%
2: .2 and 20%
3: .75 and 75%
10: (1/10) and 10%
11: (3/5) and 60%
12: (1/4) and 25%
Answer:
7x² + 5x
Dtep-by-step explanation:
(9x² + 8x) - (2x² + 3x)
9x² + 8x - 2x²- 3x
7x² + 5x