In this task you will be given a list of lists, of numbers. For every inner list, you should multiply every number in that list and put the results in your answer. The output should be a list of numbers with the same length as the number of the lists in the input list.
[[-23, 8, 17, -21, -12], [-34, 32, -22], [20, 44, 20, 18, 42], [31, 13, 34, 39]]