( 3y-5x):(5x-3y)

To simplify the expression \((3y - 5x):(5x - 3y)\), we can rewrite it as a fraction:

\[ \frac{3y - 5x}{5x - 3y} \]

Notice that the denominator \(5x - 3y\) can be rewritten as \(- (3y - 5x)\):

\[ 5x - 3y = - (3y - 5x) \]

So, we can substitute that into the fraction:

\[ \frac{3y - 5x}{5x - 3y} = \frac{3y - 5x}{- (3y - 5x)} = -1 \]

Thus, the simplified form of the expression \((3y - 5x):(5x - 3y)\) is:

\[ -1 \]