Respuesta :

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