The answer would be 4(x – 5)(x + 3)..
To explain further.
First divide the whole equation by 4
4x^2 – 8x – 60
4
Then it will look like 4(x^2 - 2x - 15)
Then expand the (x^2 - 2x - 15)
and it would be (x – 5)(x + 3)
The shortcut to this expanding is look at the last digit which is -15, what are the factors that when you add them you'll get -2? Yes It's (+3, -5)
Then just put the x