I really hate these algebra problems pretending to be geometry.
Anyway angles B and D are congruent in a parallelogram. Geometry part done.
4n - 2 = 2n + 32
2n = 34
n = 17
Answer: 17, which is the 3rd choice
I’m pretty sure there are infinite solutions as the system of equations are equivalent to each other.
Answer:

Step-by-step explanation:

After removing one black marble:

The answer is C.
90/105=6/7
Hope this helps!