The answer depends on the units used for the measurements given in the question.
2 square feet per tile.
About 0.67 sq feet per tile.
A 24" by 18" tile is 432 square inches or three square feet.
About 1.2 square feet x 63 tiles
1.78 square feet.
2 square feet per tile.
0.44444 square feet per tile.
About 0.67 sq feet per tile.
Another 53.75 square feet of tile would be needed.
A 6 ft * 12 ft tile will cover 72 square feet.
A 24" by 18" tile is 432 square inches or three square feet.
1.78 square feet
One square is equal to five square feet.
2.25 square feet
It is not clear what is meant by an "18x18 square feet" tile. 18ft * 18 ft = 324 square feet, so that one tile will be more than enough. An 18 inch by 18 inch tile cannot be a 18x18 square feet tile.
1.78 square feet.
About 1.2 square feet x 63 tiles