First, figure out the area of the tile, which can be done by breaking the tile either into 3 squares or a rectangle and a square. Either way, you can calculate the area of the tile to be 3 sq. feet. A rectangle measuring 30 ft by 20 ft would have an area of 600 sq. ft. 600/3 = 200 tiles would be needed to cover the floor, so the answer is C.