John gained 8 pounds while on vacation, but lost 12 pounds after he returned home. Which number is the additive inverse of the change in John's weight?

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.