A 20 volume encyclopedia is lined up on a shelf. Each volume has an 1 inch of page and 1/4 of inch of binding on either side. A bookwork starts on the first page of the first book and eats to last page of the last book. How many inches does it eat through?.

step-by-step explanation:

no, her answer is not correct.   we square the lengths of all sides and then determine whether the pythagorean theorem holds here:

9² + 15² = 306.   this is not equal to the square of the longest side ( that square being 395.   answer c is correct.

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step-by-step explanation:

so mark-up is 0.4 multiplied by 180 = 72