Question

Find the difference. (-ab+8a-5)-(-8ab-4)

Answer 1

-ab + 8a - 5 -(-8ab - 4) =
-ab + 8a - 5 + 8ab + 4 =
8a + 7ab - 1 <===

Answer 2

(−a)(b)+8a−5−((−8a)(b)−4) 

So first
Distribute the Negative Sign:

=(−a)(b)+8a−5+−1((−8a)(b)−4)
=(−a)(b)+8a+−5+−1((−8a)(b))+(−1)(−4)
=(−a)(b)+8a+−5+8ab+4=−ab+8a+−5+8ab+4

Then after all of that 

Combine Like Terms:=−ab+8a+−5+8ab+4
=(−ab+8ab)+(8a)+(−5+4)

So now your answer is =7ab+8a+−1