Uncle Wood has 3 wooden planks. He wants to saw each plank into 6 pieces. If each cut takes him 2 minutes, he needs a total of minutes to finish his sawing.

To saw up 1 of the planks, Uncle Wood will need to make 6 - 1 = 5 total cuts. Each one takes 2 minutes, so 1 plank will take a total of 5 × 2 = 10 minutes to cut. There are three planks, so Uncle Wood will need 3 × 10 = 30 minutes to do all of his cutting.