An airplane departs an airport and climbs to an altitude of 2,600 feet. The plane climbs 300 feet more to an altitude 2,900 feet. Which number is the additive inverse of the plane's height?

The additive inverse property a number is when you add its inverse you get 0.

I believe (if I understood the problem) they are asking the additive inverse of the last part, if so the additive inverse of 300 is - 300, so thar 300 - 300 = 0