SOLUTION: 26. Science and medicine. A plane flies 720 mi against a steady 30-mi/headwind and then returns to the same point with the wind. If the entire trip takes 10h, what is the plane’s s

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: 26. Science and medicine. A plane flies 720 mi against a steady 30-mi/headwind and then returns to the same point with the wind. If the entire trip takes 10h, what is the plane’s s      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 37237This question is from textbook Beginning Algebra
: 26. Science and medicine. A plane flies 720 mi against a steady 30-mi/headwind and then returns to the same point with the wind. If the entire trip takes 10h, what is the plane’s speed in still air?
I think the problem should be stated like this but I'm not sure. I just can't seem to get it to work.
(720/x-20)+(720/x+20)=12 This question is from textbook Beginning Algebra

Found 2 solutions by checkley71, Paul:
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
720/(x+30)+720/(x-30)=10 or [720(x-30)+720(x+20)]/x+30)(x-30)=10 or
(720x-21600+720x+216000)/(x~2-900)=10 or 10x~2-9000=1440x or
10x~2-1440x-9000 or x~2-144x-900 or (x-150)(x+6)=0 or x=150mph

Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
Where did you get 12 and 20 from?
Since the entire time for the trip is 10h, it is going to be SPEED 1 + SPEED 2.
EQUATION:
720%2F%28x-30%29%2B720%2F%28x%2B30%29=10
720[(x+30)+(x-30)]=10[(x+30)(x-30)]
720%282x%29=10%28x%5E2-900%29
1440x=10x%5E2-9000
x%5E2-144x-900=0
x+=+%28-%28-144%29+%2B-+sqrt%28+%28-144%29%5E2-4%2A1%2A%28-900%29+%29%29%2F%282%2A1%29+
x=150
Hence, the speed of the plane is 150mph.