I might not be right here but i think its C, now before you just leave to circle the answer, find out why: Multiply 54 and 8 to find out how many TOTAL square tiles you need. The answer would be 432. Then since it says 8 groups of 4 blue tiles, this mean 8*4, which is 32. 32 of the TOTAL square tiles would be blue. subtract 432-32 to get 400 because the question is asking for the WHITE tiles. this is why you subtract the total tiles from the blue tiles to get the white tiles.