###### Exercise 84

Each page of a book is \({6 {\textstyle\frac{1}{2}}}\) inches in height, and consists of a header (a top margin), a footer (a bottom margin), and the middle part (the body). The header is \({{\frac{2}{9}}}\) of an inch thick and the middle part is \({5 {\textstyle\frac{8}{9}}}\) inches from top to bottom.

What is the thickness of the footer?

The footer is of an inch thick.