If you are given with all the tree sides of the triangle, you may solve for all the angles through the Law of Cosines,
c² = a² + b² - 2ab(cos C)
where angle C is the angle opposite the side c. You may use the same equation to get the values of the remaining angle. Additionally, if you already have one known angle, you can solve for the rest of the angles by Law of Sines,
a / sin A = b / sin B = c / sin C
A) 4
∠14 & ∠12
∠11 & ∠13
∠10 & ∠8
∠7 & ∠9
vertical angles are angles directly opposite of each other and are of the same measurement.
hope this helps
7844=7400(1+(8/12)r)
Solve for r
R=0.09*100=9%
Firstly, we'll fix the postions where the 
women will be. We have 
forms to do that. So, we'll obtain a row like:
The n+1 spaces represented by the underline positions will receive the men of the row. Then,
Since there is no women sitting together, we must write that 
. It guarantees that there is at least one man between two consecutive women. We'll do some substitutions:
The equation (i) can be rewritten as:
We obtained a linear problem of non-negative integer solutions in (ii). The number of solutions to this type of problem are known: ![\dfrac{[(n)+(m-n+1)]!}{(n)!(m-n+1)!}=\dfrac{(m+1)!}{n!(m-n+1)!}](https://tex.z-dn.net/?f=%5Cdfrac%7B%5B%28n%29%2B%28m-n%2B1%29%5D%21%7D%7B%28n%29%21%28m-n%2B1%29%21%7D%3D%5Cdfrac%7B%28m%2B1%29%21%7D%7Bn%21%28m-n%2B1%29%21%7D)
[I can write the proof if you want]
Now, we just have to calculate the number of forms to permute the men that are dispposed in the row: 
Multiplying all results:
