To solve this problem you must follow the steps below:
1. The problem says that:
- The hot air balloon is at an altitude of 240 feet.
- It descends at 30 feet per minute.
2. Therefore, you have:
x: the time in minutes.
y: the altitute in feet.
3. Keeping all this information on mind, you can write the following equation:
y=240-30x
4. Therefore, as you can see, the answer is:
y=240-30x