You are preparing to tile the floor of a rectangular room that is 15.5 feet by 18 feet in size. the tiles you plan to use are squares, measure 12 inches on each side, and are sold in boxes that contain enough tiles to cover 25 square feet. each box costs $30. to determine the cost of materials you multiply 15.5 by 18, divide by 25, round up to the next whole number, and multiply by 30. is this correct? a) yes. b) no, you need to round down and then multiply by 30. c) no, you need to round down and then multiply by 144. d) no, you need to divide by 144, round up, and then multiply by 30. e) no, you need to divide by 144, round down, and then multiply by 30.