
That's 7.68% = 7.7% (rounded)
Note: C(5, 4) is the number of combinations of 5 things taken 4 at a time. You may have seen this written as

In general,
Hsyshshshbshsbsbbajshshsjwjwnw
Both have the same denominator
Remove the denominator
5=n
Answer:
v=37 degrees; u=53 degrees