You always want your best programmers on your team, so start by sorting the number of problems
each programmer can solve, largest first. Then go through each possible team size k=1..n, and compute:
	([sum of the first k programmers] + [kth bonus])/k
Find the largest of all of those.

Here is some python code:

n = int(input())
a = list(map(int, input().split()))
s = list(map(int, input().split()))
s.sort()

ans = 0
tot = 0
for i in range(n):
    tot += s[n-i-1]
    tans = (tot + a[i]) / (i + 1)
    ans = max(ans, tans)
print(ans)