We break all the bracket out :
-0.75 + 2/5 + 0.4 - 3/4
2/5 = 0.4
-3/4 = -0.75
So, we have : -0.75 + 0.4 + 0.4 - 0.75
= (-0.75 - 0.75) + (0.4 + 0.4) = -1.5 + 0.8 = -0.7
What are two factors of -10 that add up to 9?
They are 10 and -1. 10*-1=-10
(x+10)(x-1)