To relate the number of novels \( N \) that Ahmad needs to read to the number of months \( M \), we can use the following equation:
\[ N = 6M \]
This means that for every month \( M \), Ahmad reads 6 novels.
Now, to find the number of novels Ahmad needs to read in 13 months, we can substitute \( M = 13 \) into the equation:
\[ N = 6 \times 13 \] \[ N = 78 \]
Therefore, the answers are:
Equation: \( N = 6M \)
Number of novels in 13 months: 78 novels