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.
[[-49, 14, 12, -42, 50], [-24, -38, -42, -7], [34, 31], [-18, -13, -15]]