Final answer:
The stack of books that is 69 inches high can be converted to 5 feet and 9 inches.
Step-by-step explanation:
The stack of books that is 69 inches high can be converted to feet and inches by dividing the total height by 12. Since there are 12 inches in a foot, dividing 69 inches by 12 gives us 5 feet and a remainder of 9 inches. Therefore, the stack of books is 5 feet and 9 inches high.