The answer is going to be five because five plus five is ten!!!
Lets try
centimeter is about 1/2 of a inch
if 28 square cm, the book coould be about 4m by 7cm (aoub the size of a recipt)
if 28 square in the book could be about 4in by 7in (regular size)
I would guess 28 square INCHES (cm is too smal)
The 2 numbers you multiply to get 18 are 6 and 3.
