def average(numbers):
    total = float(sum(numbers))
    return total
    average = total / len(numbers)
    return average

Define a function called average that has one argument, numbers.
Inside that function, call the built-in sum() function with the numbers list as a parameter. Store the result in a variable called total.
Like the example above, use float() to convert total and store the result in total.
Divide total by the length of the numbers list. Use the built-in len() function to calculate that.
Return that result.