Answer:
Step-by-step explanation:
a=3400t+600, we put in 21,000 for a. Because we have to find 't' when 'a' is 21,000.
which will give us 21,000 = 3400t+600.
Then,Subtract 600 to both sides to get 20,400 = 3400t
Divide both sides by 3,400 and you get 6 = t.
The ans is 6 minutes. The plane will take 6 min to reach the altitude 21,000 feet
