Final answer:
The altitude of the hot air balloon after 10 minutes is 60 feet.
Step-by-step explanation:
The equation given, 210 – 15t, represents the altitude of a hot air balloon over time, where t represents time in minutes and H(t) represents the altitude in feet. To find the altitude after 10 minutes, we substitute 10 into the equation: 210 – 15(10). Simplifying this, we get 60 feet, so after 10 minutes, the hot air balloon is at an altitude of 60 feet.