Area = L x H
area = 20 x 15 = 300 square feet
The total number of books on the shelf is 12 books
Given the following parameters
Total number of puzzle books on the shelf = 30 books
If the number of puzzle books is 25 of all the books on the shelf, the total number of books on the shelf is expressed as:
= 2/5 of 30
= 2/5 * 30
= 2 * 6
= 12
Hence the total number of books on the shelf is 12 books
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Answer: 
Explanation: Note that

To evaluate the integral in the boxed equation, let

. Then,
So,

Since y = 1 when x =0, equation (1) becomes

With the value of C, equation (1) becomes

Hence, if y = 3,