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].
Q: [-80, 99, -49, -90, 63, 15, 39, -5, -17]
A: 
[9.5, 25.0, -69.5, -13.5, 39.0, 27.0, 17.0, -11.0]