Factor completely 5x2 – 50x + 120
answer
(x – 4)(5x – 30)
(5x – 15)(x – 8)
5(x – 3)(x – 8)
5(x – 4)(x – 6)

The answer is 5(x - 4)(x - 6)
 
5x² – 50x + 120 = 5*x² -  5*10x + 5*24
                           = 5(x² - 10x + 24)
                           = 5(x * x - 4x - 6x + 6*4)
                           = 5(x(x - 4) - (6x - 6*4))
                           = 5((x(x - 4) - 6(x - 4))
                           = 5(x - 4)(x - 6)