it takes billy an hour to rase to his friends house and two hours if he went 20 mph slower how far away does billy's friend live?

40 miles.
you are doubling the amount of time it takes when it’s -20mph, so multiply 20 by 2 to get 40 miles

The additive inverse is the opposite of a number, meaning that if a number is positive, it's opposite is negative and vise versa. John's total weight change was -4, because he gained 8 and lost 12. Because of the additive inverse property, we know that the additive inverse of -4 (his weight change) is 4.