Use substitution.
anywhere you see "a" , than you would plug in b + 2 in for it so....
(b - (b + 2)^4
now take the negative sign and distribute it "+"
so b - b is 0, than 0 - (-2) is -2.
so what is (-2)^4 ????? it would become positive 16
The answer to that would be 0.0098.

Here we go ~
The air plane descends 15 feels every 1.45 seconds, so it's unit rate is :

Now we have to calculate the descent in 3.5 minutes ~


So, the airplane descends 2172.41 feels in three and a half minutes ~