If Jina reads 90 pages a day, it will take her more than 4 days to finish reading a
book. If she reads 80 pages a day, she will take less than 5 days. If the number of
days Jina takes to finish reading is the same as the number of pages she reads
every day, how many pages she must read every day?
Let's assume the number of pages Jina reads every day is x.
According to the first statement, if Jina reads x pages a day, it will take her more than 4 days to finish reading a book.
So, we can write the inequality as x * 4 < number of pages in the book.
According to the second statement, if Jina reads x pages a day, it will take her less than 5 days to finish reading a book.
So, we can write the inequality as x * 5 > number of pages in the book.
Combining the two inequalities, we get x * 4 < number of pages in the book < x * 5.
Since we know that the number of days Jina takes to finish reading is the same as the number of pages she reads every day, the number of pages in the book should be between x * 4 and x * 5.
This leaves us with only one possibility, x = 4.
So, Jina must read 4 pages every day.
Let's analyze the given information step-by-step to find the solution:
1. If Jina reads 90 pages a day, it will take her more than 4 days to finish reading a book.
2. If she reads 80 pages a day, she will take less than 5 days to finish reading a book.
3. We know that the number of days Jina takes to finish reading is the same as the number of pages she reads every day.
To find the number of pages Jina must read every day, let's consider the first scenario:
1. If Jina reads 90 pages a day, it will take her more than 4 days to finish reading a book.
Since the number of days is more than 4, it means it takes her at least 5 days to finish the book.
Now let's consider the second scenario:
2. If she reads 80 pages a day, she will take less than 5 days to finish reading a book.
Since the number of days is less than 5, it means it takes her 4 days to finish the book.
Now we have conflicting information, but we know that the number of days Jina takes to finish reading is the same as the number of pages she reads every day. Therefore, the number of pages she must read every day must be 4 pages.
So, Jina must read 4 pages every day.