SOLUTION: I need help with this problem. A plane flies 720 mi against a steady 30 mi/h headwind and then returns to the same point with the wind. If the entire trip takes 10 h, what is th

If you need immediate math help from PAID TUTORS right now, click here. (paid link)
Click here to see ALL problems on Travel Word Problems

Question 96041This question is from textbook Beginning Algebra
: I need help with this problem.
A plane flies 720 mi against a steady 30 mi/h headwind and then returns to the same point with the wind. If the entire trip takes 10 h, what is the plane's speed in still air?
Here is what I know: If r is the rate of the plane (in miles per hour)in still air, then the rate against the wind would be r - 30 and the rate with the wind would be r + 30. I don't know what to do after this point.This question is from textbook Beginning Algebra

Answer by checkley71(8403) (Show Source):
You can put this solution on YOUR website!
720/(X-30)+720/(X+30)=10
[720(X+30)+720(X-30)]/(X-30)(X+30)=10
(720X+21600+720X-21600)/X^2-900=10 NOW CROSS MULTIPLY:
10X^2-9000=1440X
10X^2-1440X-9000=0 FACTOUT THE 10
10(X^2-144X-900)=0
(X-150)(X+6)=0
X-150=0
X=150 MPH IS THE SPEED FO THE AIRPLANE IN STILL AIR.
PROOF
720/(150-30)+720/(150+30)=10
720/120+720/180=10
6+4=10
10=10