60 inches is the answer.
In this case the amount of cups do not matter only the height because that's what it's asking for.
If each stack is 6 inches we would have to multiply that by 10 because there are 10 stacks.
6 x 10 = 60 inches tall
X = excellent condition books
y = fair condition books
2.50x + 0.50y <== ur expression
Answer:
Maybe the answer must be 90°
First, let's expand the right side. Now our equation is

Now, we gather all the terms with x in it on the left side, and the numbers without x on the right. We get:

And then we can make this

We divide both sides by 12 to get x on its own, so x = 13/12 or 1.08