To simplify \( 32 \sqrt{5} - 17 \sqrt{5} \), you can combine the like terms:
\[ 32 \sqrt{5} - 17 \sqrt{5} = (32 - 17) \sqrt{5} \]
Calculating \( 32 - 17 \):
\[ 32 - 17 = 15 \]
So, \( 32 \sqrt{5} - 17 \sqrt{5} = 15 \sqrt{5} \).
Thus, the expression in simplest form is:
\[ \boxed{15 \sqrt{5}} \]