a textbook page measures 6 inches by 9 inches. there is a margin of uniform width around all four sides of the page leaving 28 square inches for printing. find the width and height of the printing area
(6-2w)(9-2w) = 28
4w^2 - 30w + 54 = 28
4w^2 - 30w + 26 = 0
(2w-13)(2w-2) = 0
w = 2 or 13/2
13/2 is too big, since the book is only 6" wide.
so, the border is 1" wide.
check: 4x7 = 28