Answer:
-54ft/min (-54 feet per minute)
Step-by-step explanation:
To solve this, we need to use background knowledge to get one of our missing numbers.
Since we know an hour is 60 minutes, we need to do 3,240/60 to receive our unit rate. So, 3,240/60 would equal 54.
But, the balloon is descending (going down), so we need to make our answer negative (54 -> -54)
Therefore, the hot air balloon is descending 54 feet per minute, or -54ft/min.