Answer:
4(-5a + 3b - 2)
Step-by-step explanation:
Aside from changing the order of the terms so that the "a" term comes first and the "b" term second, there's nothing you can do with this expression -20a -8 + 12b. But notice that 4 is a factor common to all three terms, and therefore it can be factored out:
Rearranging the terms, we get
-20a + 12b - 8 = 4(-5a + 3b - 2)
