Whom ever wrote this problem, did not give the unit of measurement (yards, feet, meters, etc.) so, I am going to presume that the 12 by 12 tile is in inches, and the 15 by 15 is in feet.
If my presumption was correct the answer is 15 tiles. Because a 12 by 12 tile is = to 1 square foot. How many 1's fit into 15? 15!
Well, not exactly.....
You need to multiply 15 X 15 to get the square footage and that will give you
the number of tiles needed since the tiles are 1 ft square. 15 x 15= 225. So you
need 225 tiles. And add extra tiles for breakage...
585
168
13 boxes with 13 tiles in each
The tile is bigger than the area that you want to cover (12x12 > 10x11) so one tile will do. <><><><><> However, if you meant 12x12 INCH tiles, and a 10x11 FOOT room, you would need 110 tiles.
123 will cover it. Get extras.
144 tiles
585
168
13 boxes with 13 tiles in each
The tile is bigger than the area that you want to cover (12x12 > 10x11) so one tile will do. <><><><><> However, if you meant 12x12 INCH tiles, and a 10x11 FOOT room, you would need 110 tiles.
375
154
122
123 will cover it. Get extras.
If you're talking floor tiles as opposed to wall tiles and by 12x12 you mean they are 12 inches square, then the answer is 300. Because each tile is one square foot and a 15'x20' room is 300 square feet. Simple, eh?
To calculate the number of 18x18 ceramic tiles needed for a 12x12 room, first determine the area of the room and the area of one tile. The area of the room is 144 square feet (12x12), and the area of one tile is 2.25 square feet (1.5x1.5). Dividing the room area by the tile area, you'll need about 64 tiles (144 ÷ 2.25). It's advisable to purchase a few extra tiles to account for cuts and breakage.
Since there are no units given it is not possible to answer the question. The units used for measuring the tiles must be different from those used for the room.