To factor the expression \( 18m - 24n \) using the greatest common factor (GCF), we first need to identify the GCF of the coefficients 18 and 24.
- The factors of 18 are \( 1, 2, 3, 6, 9, 18 \).
- The factors of 24 are \( 1, 2, 3, 4, 6, 8, 12, 24 \).
The common factors are \( 1, 2, 3, 6 \), and the greatest of these is \( 6 \).
Now, we can factor out the GCF, which is \( 6 \):
\[ 18m - 24n = 6(3m - 4n) \]
So, the factored form of \( 18m - 24n \) is:
\[ 6(3m - 4n) \]