30y^2√(y-1) -105y^2√(y-1) +45y√(y-1)

You can factor out ’15’ and ‘y’ and ‘√(y-1)’

15y√(y-1)(2y - 7y + 3)

combine like terms within the parentheses

15y√(y-1)( -5y + 3) <====

- OR -

15y√(y-1)(3 - 5y) <==== if you prefer