instruction:
In this task you will be given a list of numbers and you need to subtract every value in the list with the index it is at. The index of an elements shows its numerical order in the list(for example, in the list [7,10,4,5], the index of 7 is 1 and the index of 4 is 3)  You should start the index at 1, so the first element in the list will be subtracted by one. For every element in the list you need to find "element - index" where the index of the beginning element is 1 and increments by 1 for each element. Put your result list in brackets.
question:
[15, -10]
answer:
[14, -12]


question:
[-9, -8, 12, 13, -6, -6, 20]
answer:
[-10, -10, 9, 9, -11, -12, 13]


question:
[11, -18, -6, 4, 0, -7, 2, 18, 12]
answer:

[10, -20, -9, 0, -5, -13, -5, 10, 3]