You have a problem somewhere:
Test3:

  input a = [[2, 7], [1, 3], [1, 12]]
  èxpected output b = [[24, 84], [28, 84], [7, 84]]

[[10, 36], [12, 36], [3, 36]] is your output which is wrong. It is not the input.

Which test? By the way look at the top of the page and see how many people passed the Python kata. Cheers.