To simplify the expression \( 7(2x - 4) \) using the distributive property, you multiply 7 by each term inside the parentheses.
\[ 7(2x) - 7(4) \]
Calculating each term, we get:
\[ 14x - 28 \]
So, the simplified expression is:
\[ \boxed{14x - 28} \]