To simplify the expression \((9x^3y - 5x^2y^2 + x^2y) : (-3xy)(9x^3y - 5x^2y^2 + x^2y) : (-3xy)\), we first identify the operation or formula being used. The `:` denotes division; therefore, we can rewrite the expression as follows:

\[
\frac{9x^3y - 5x^2y^2 + x^2y}{-3xy} \cdot \frac{1}{-3xy}
\]

Let's simplify the numerator, \(9x^3y - 5x^2y^2 + x^2y\), which can be factored. We can factor out \(x^2y\) from the terms:

\[
= x^2y(9x - 5y + 1)
\]

Now substituting this back into the expression, we have:

\[
\frac{x^2y(9x - 5y + 1)}{-3xy} \cdot \frac{1}{-3xy}
\]

Next, we can simplify the first fraction:

\[
= \frac{x^2y(9x - 5y + 1)}{-3xy} = \frac{x^2(9x - 5y + 1)}{-3}
\]

The \(y\) in the numerator and denominator cancels out, provided \(y \neq 0\):

Now we can express this as:

\[
\frac{x^2(9x - 5y + 1)}{-3}
\]

Now we need to multiply this with \(\frac{1}{-3xy}\):

Combining these gives:

\[
\frac{x^2(9x - 5y + 1)}{-3} \cdot \frac{1}{-3xy} = \frac{x^2(9x - 5y + 1)}{9xy}
\]

Now we can simplify the fraction \( \frac{x^2}{xy} = \frac{x}{y} \), provided \(y \neq 0\):

Thus, the simplified expression is:

\[
\frac{x(9x - 5y + 1)}{9y}
\]

Therefore, the final result of the original expression is:

\[
\frac{x(9x - 5y + 1)}{9y}
\]

This accounts for all instances where \(y\) is not equal to zero.