Factor completely 4x2 – 8x – 60
answer
(4x – 20)(x + 3)
4(x – 1)(x + 15)
4(x – 5)(x + 3)
(4x – 4)(x + 15)

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