Step 1: Understanding the Concept: 
This is an overlapping sets problem. We can organize the information in a 2x2 table. 
Let F be Fiction, NF be Non-Fiction. 
Let S be Spanish, NS be Not Spanish. 
We are given:
    
 Total Books = 80
    
 Total Fiction (F) = 24
    
 Total Spanish (S) = 23
The question asks for the number of books that are both Fiction and Spanish, which is the intersection of F and S. Let's call this number \(x\). 
Step 2: Key Formula or Approach: 
We can use variables to represent the quantities.
Let \(x\) = number of Fiction books in Spanish.
The total number of Fiction books is 24.
So, the number of Fiction books not in Spanish is \(24 - x\).
The total number of Spanish books is 23.
So, the number of Non-Fiction books in Spanish is \(23 - x\). 
Step 3: Detailed Explanation: 
Analyze Statement (1): Of the fiction books, there are 6 more that are not written in Spanish than are written in Spanish. 
This can be written as an equation:
(Number of Fiction books not in Spanish) = (Number of Fiction books in Spanish) + 6 
Using our variables:
\[ 24 - x = x + 6 \]
Now, we solve for \(x\):
\[ 18 = 2x \]
\[ x = 9 \]
Since we found a unique value for \(x\), statement (1) is sufficient. 
Analyze Statement (2): Of the books written in Spanish, there are 5 more nonfiction books than fiction books. 
This can be written as an equation:
(Number of Non-Fiction books in Spanish) = (Number of Fiction books in Spanish) + 5 
Using our variables:
\[ 23 - x = x + 5 \]
Now, we solve for \(x\):
\[ 18 = 2x \]
\[ x = 9 \]
Since we found a unique value for \(x\), statement (2) is sufficient. 
Step 4: Final Answer: 
Each statement alone is sufficient to determine the number of fiction books written in Spanish.