A hot-air balloon is sighted at an
altitude of 800 feet and appears to be
descending at a steady rate of 20 feet
per minute. Spectators are
wondering how the altitude of the
balloon is changing
as time passes.

A hotair balloon is sighted at an altitude of 800 feet and appears to be descending at a steady rate of 20 feet per minute Spectators are wondering how the alti class=