question 2 is a bit tricky...see below
"Sets
There are currently five major domino sets commercially available. They are Double Six, Double Nine, Double Twelve, Double Fifteen, and Double Eighteen, which is the largest set available commercially. Here are the number of tiles and points (pips or spots) in each set.
Double 6: 28 tiles, 168 pips
Double 9: 55 tiles, 495 pips
Double 12: 91 tiles, 1092 pips
Double 15: 136 tiles, 2040 pips
Double 18: 190 tiles, 3420 pips "
I'm guessing they mean the first one