#### Answer

3y(y - 5)

#### Work Step by Step

To factor this polynomial, we must factor out the GCF (greatest common factor). With 3 and 15, the GCF is 3. With y$^2$ and y, the GCF is simply "y." The GCF is therefore 3y.
Now, write each term as a product of the GCF (3y).
3y$^2$ - 15y = 3y(y) - 3y(5)
As both of the terms have a 3y, we can factor out a 3y from this expression:
3y(y - 5)