5y-15+2y²-6y

To simplify the expression \(5y - 15 + 2y^2 - 6y\):

1. Combine like terms.
   • The terms with \(y\): \(5y - 6y = -1y\) or \(-y\).
   • The constant term is \(-15\).
   • The \(2y^2\) term remains as it is.

Putting it all together, we get: \[ 2y^2 - y - 15 \]

So, the simplified expression is: \[ 2y^2 - y - 15 \]