Exercise 40 Page 134

Why do we change the sign when dividing two negative numbers? - a/- b=a/b Try thinking about it in terms of English instead. When you use a double negative in conversation, it changes the meaning to be positive.

Your friend: Why are you going to the school play this Saturday?
You: I would never NOT go to a school play! I get extra credit in my English class if I go!

Saying never not means you always go. Math works the same way!