average([3, 0]) resulted in an error: ‘int’ object has no attribute ‘getitem’

is an error when i wrote this code in (5.Its Okey to be Average) in last part of learn python 2 , pls whats the problem:

```
lloyd = {
"name": "Lloyd",
"homework": [90.0, 97.0, 75.0, 92.0],
"quizzes": [88.0, 40.0, 94.0],
"tests": [75.0, 90.0]
}
alice = {
"name": "Alice",
"homework": [100.0, 92.0, 98.0, 100.0],
"quizzes": [82.0, 83.0, 91.0],
"tests": [89.0, 97.0]
}
tyler = {
"name": "Tyler",
"homework": [0.0, 87.0, 75.0, 22.0],
"quizzes": [0.0, 75.0, 78.0],
"tests": [100.0, 100.0]
}
# Add your function below!
students = [lloyd, alice, tyler]
def subtotal(students):
total = 0
for x in students:
total = sum(x["homework"]) + sum(x["quizzes"]) + sum(x["tests"])
return total
def length(students):
for x in students:
leng = len(x["homework"]) + len(x["quizzes"]) + len(x["tests"])
return leng
def average(Y):
average = subtotal(Y) / length(Y)
return average
for x in students:
print x["name"]
print average(students)
print
```