A hot air balloon is flying at an altitude of 870 feet. It descends at a rate of 15 feet per minute

Question

a) write an equation that gives the altitude (in feet) of the balloons as a function of the time (in minutes) since it began its descent.

b) Find the time it takes the balloon to reach an altitude of 12 feet. Explain your reasoning

Answer 1

If x is the altitude after t minutes, x=870-15t because it loses 15' for each minute. When x=12, 12=870-15t, so t=(870-12)/15=858/15=57.2 mins or 57m 12s.