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.
to calculate the number of boxes you need to complete the job you multiply 15.5 by 18 and then divide by 144 to determine that you need just under 2 boxes. is this correct?
a) yes.
b) no, you need to multiply 18 by 2, then divide by 15.5 to determine the number of boxes.
c) no, after multiplying 15.5 by 18 you need to divide by 25 to determine the number of boxes.
d) no, after multiplying and dividing you need to multiply by 25 to determine the number of boxes.

C) No, after multiplying 15.5 by 18 you need to divide by 25 to determine the number of boxes.

Step-by-step explanation:

The dimensions of the rectangular room are 15.5 feet x 18 feet.  Which is a total area of:  15.5 x 18 = 279 ft².

The tiles being used are 12 inches x 12 inches or 1 foot x 1 foot.  Since there are 25 tiles in each box, it can cover an area of 25 ft ².  

When doing calculations with measurements, the measurements must be the same.  For instance, you can not divide square feet by inches because they are different measurements.  However, you can divide by square feet.  To the total square footage of the room (279 ft²) can be divided by the amount of square feet covered by each box (25 ft²):  279/25 = 11.16 or a minimum of 12 boxes would be needed.