Answer:
a) Josh likely made the negative and positive multiplication error.
b) -20a-8+12b
= -4(5a+2-3b)
Step-by-step explanation:
To check if you are correct, you can always simplify it again:
-4(5a+2-3b)
=-20a-8+12b
Remember:
Negative times negative equals to positive, negative times positive equals to negative!
I hope this is helpful! :)