document.write( "Question 1208722: A plane flies from Penthaven to Jackson and then back to Penthaven. When there is no wind, the round trip takes $5$ hours and $20$ minutes, but when there is a wind blowing from Penthaven to Jackson at $70$ miles per hour, the trip takes $9$ hours. How many miles is the distance from Penthaven to Jackson? \n" ); document.write( "
Algebra.Com's Answer #847127 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
A plane flies from Penthaven to Jackson and then back to Penthaven. When there is no wind, the round trip takes $5$ hours and $20$ minutes, but when there is a wind blowing from Penthaven to Jackson at $70$ miles per hour, the trip takes $9$ hours. How many miles is the distance from Penthaven to Jackson?
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document.write( "Let the ground speed of the plane when there is no wind = R mph\r\n" );
document.write( "When the wind is a tail wind of 70 mph, the ground speed is R+70 mph\r\n" );
document.write( "When the wind is a head wind of 70 mph, the ground speed is R-70 mph\r\n" );
document.write( "Let T1 = the time to go from P to J against a head wind.\r\n" );
document.write( "Let T2 = the time to go from J to P with a tail wind.\r\n" );
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document.write( "                          |distance|  rate  |  time  |\r\n" );
document.write( "P to J to P (no wind)     |  2D    |   R    | 5 2/3  |\r\n" );
document.write( "P to J (head wind)        |   D    | R-70   |   T1   |\r\n" );
document.write( "J to P (tail wind)        |   D    | R+70   |   T2   |      \r\n" );
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document.write( "Find a solver online for nonlinear systems. Perhaps\r\n" );
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document.write( " https://www.wolframalpha.com/\r\n" );
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document.write( "Use t for T1 and T for T2\r\n" );
document.write( "since they don't usually take subscripted letters.\r\n" );
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document.write( "D≈325.89, R≈115.02, t≈1.7614, T≈7.2386\r\n" );
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document.write( "So the distance is approximately 326 miles.\r\n" );
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document.write( "Edwin

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