Update average.py (#908)

Reduced lines of code and extra processing on the line: n += 1

Author: lordsarcastic

maths/average.py

@@ -1,11 +1,10 @@
 def average(nums):
     sum = 0
-    n = 0
     for x in nums:
       sum += x
-      n += 1
-    avg = sum / n
+    avg = sum / len(nums)
     print(avg)
+    return avg
 
 def main():
   average([2, 4, 6, 8, 20, 50, 70])