Distribute the term outside the parenthesis across the terms inside: 
1. Multiply \(5y\) by \(1\): 
5y \cdot 1 = 5y 
2. Multiply \(5y\) by \(-y\): 
5y \cdot (-y) = -5y^2 
Combine these results: 
5y - 5y^2 
Thus, the simplified form is: 
5y - 5y^2 
The answer is: 
5y - 5y^2