To find out how many patrons borrow novels from the local library, we can set up a proportion based on the survey data.
From the survey, 3 out of 80 patrons borrow novels. We can express this as follows:
\[ \frac{3}{80} \]
Now, we want to find out how many patrons borrow novels out of the total of 345 patrons. Let \( x \) represent the number of patrons who borrow novels:
\[ \frac{3}{80} = \frac{x}{345} \]
To solve for \( x \), we can cross-multiply:
\[ 3 \times 345 = 80 \times x \]
Calculating \( 3 \times 345 \):
\[ 3 \times 345 = 1035 \]
Now the equation becomes:
\[ 1035 = 80x \]
Next, solve for \( x \) by dividing both sides by 80:
\[ x = \frac{1035}{80} \approx 12.9375 \]
Rounding this to the nearest whole number gives us:
\[ x \approx 13 \]
Thus, approximately 13 patrons borrow novels when they visit the library.