Ineed with my math. i don't understand any of it. : (

This is very easy just alot of terrible numbers lol.

If she goes "down" for 90 SEC  that means she is moving Negative.
So she moves for 90 seconds at a Rate of 3.5 Feet per second
Which means every second she goes down she will subtract 3.5 Ft
Since she is moving for 90 SEC then this will be the equation
 Feet will be negative because she is going down.
-3.5 X 90=?  You might need a calculator.

Now that she has gone down she decided to go up.  For 30 seconds at a different rate. 2.2 Seconds. So now since she is going up it is Increasing. 
Feet will be Positive because she is going up now.
This is the equation 
2.2 X 30=? 
First you want to add both the equations you solved so far.
Now she wants to go to Exactly 0 . So she decides to go up really fast!
So when you get the amount.  She wants to Increase by 4.8 FT Per SEC

So you take the amount you added which should be negative 
And put it into an equation.
 
4.8 Divided by ( the equation you added) = ? SEC

SEC= SECONDS FT= FEET