Teacher: In this task you are given a list of numbers and you need to find the average of each two consecutive values. The average of two numbers a and b is calculated as: (a + b) /2. The output should be a list of the averages of each two consecutive values. A list is presented with two brackets and comma-separated values, like: [1,2,3].
Teacher: Now, understand the problem? If you are still confused, see the following example:
[-4, 7, 3]
Solution: [1.5, 5]
Reason: To create the answer, we should first calculate the average of -4 and 7, that is: (-4 + 7 ) / 2 = 1.5, so the first element of the answer is 1.5. Then, we need to calculate the average of 7 and 3, that is: 5. So the second element of the answer is 5.

Now, solve this instance: [73, 40, -63, -57, -80, -83, 11, -31, -20]
Student:
[56.5, -11.5, -60.0, -68.5, -81.5, -36.0, -10.0, -25.5]