
Answer:
10,000
Step-by-step explanation:
f = feet above ground
r = rate of descent
m = minutes
Â
f = 30000 - r · m
f = 30000 - 20000m
Â
After five minutes:
Â
f = 30000 - 2000(5)
f = 30000 - 10000
f = 20000
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After five minutes the plane is at 10,000. feet.