(2x -5y)^2  - (15y - 6x)^2 + |xy - 90|

To simplify the expression

\[
(2x-5y)^2 - (15y-6x)^2 + |xy - 90|(2x-5y)^2 - (15y-6x)^2 + |xy - 90|,
\]

let's first simplify the individual components.

1. **Recognize the structure of the expression**:
- We have two main parts in the expression: \((2x-5y)^2\) and \((15y-6x)^2\).
- Each of these appears multiple times.

2. **Reorganizing and combining like terms**:

Combine the terms:
\[
(2x-5y)^2 + |xy - 90|(2x-5y)^2 - (15y-6x)^2 - (15y-6x)^2 + |xy - 90|
\]

This can be rewritten as:
\[
\left(1 + |xy - 90|\right)(2x-5y)^2 - 2(15y-6x)^2 + |xy - 90|.
\]

3. **Leaving the expression simplified**:
So, the expression simplifies to:

\[
(1 + |xy - 90|)(2x-5y)^2 - 2(15y-6x)^2 + |xy - 90|.
\]

At this point, the expression is simplified but not evaluated further without specific values for \(x\) and \(y\). If you want to evaluate it with particular values, please provide those.