document.write( "Question 101010This question is from textbook Algebra I
\n" ); document.write( ": It takes 1 hour longer to fly to St. Paulat 200mi/h than it does to return at 250 mi/h. How far away is St. Paul? \n" ); document.write( "
Algebra.Com's Answer #73520 by Edwin McCravy(20056)\"\" \"About 
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It takes 1 hour longer to fly to St. Paul at 200mi/h than it does to return at 250 mi/h. How far away is St. Paul?
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document.write( "Make a DRT-chart:\r\n" );
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document.write( "             DISTANCE    RATE    TIME\r\n" );
document.write( "Going                                \r\n" );
document.write( "Returning                                \r\n" );
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document.write( "------------------------------------\r\n" );
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document.write( "Let the time required to return be t.\r\n" );
document.write( "So fill in t for the \"Returning time\".\r\n" );
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document.write( "             DISTANCE    RATE    TIME\r\n" );
document.write( "Going                                  \r\n" );
document.write( "Returning                           t\r\n" );
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document.write( "------------------------------------\r\n" );
document.write( "We read:\r\n" );
document.write( ">>...1 hour longer to fly to St. Paul...<<\r\n" );
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document.write( "So we fill in the \"Going time\" box with t+1:\r\n" );
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document.write( "             DISTANCE    RATE    TIME\r\n" );
document.write( "Going                             t+1\r\n" );
document.write( "Returning                           t\r\n" );
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document.write( "------------------------------------\r\n" );
document.write( "We read:\r\n" );
document.write( ">>...fly to St. Paul at 200mi/h...<<\r\n" );
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document.write( "So we fill 200 in the \"Going rate\" box\r\n" );
document.write( "in the chart:\r\n" );
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document.write( "             DISTANCE    RATE    TIME\r\n" );
document.write( "Going                     200     t+1\r\n" );
document.write( "Returning                           t\r\n" );
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document.write( "------------------------------------\r\n" );
document.write( "We read:\r\n" );
document.write( ">>...to return at 250 mi/h...<<\r\n" );
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document.write( "So we fill 250 in the \"Returning rate\"\r\n" );
document.write( "box in the chart:\r\n" );
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document.write( "             DISTANCE    RATE    TIME\r\n" );
document.write( "Going                     200     t+1\r\n" );
document.write( "Returning                 250       t\r\n" );
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document.write( "------------------------------------\r\n" );
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document.write( "Now we use the formula \r\n" );
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document.write( "DISTANCE = RATE × TIME\r\n" );
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document.write( "to fill in the \"Distance Going\" and the \r\n" );
document.write( "\"Distance Returning\" boxes.\r\n" );
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document.write( "             DISTANCE    RATE    TIME\r\n" );
document.write( "Going        200(t+1)     200     t+1\r\n" );
document.write( "Returning     250t        250       t\r\n" );
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document.write( "------------------------------------\r\n" );
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document.write( "Now we form the equation by realizing that\r\n" );
document.write( "the \"Distance Going\" equals the \"Distance\r\n" );
document.write( "Returning\". So we set what's in the \"Distance\r\n" );
document.write( "Going\" box in the chart above, namely 200(t+1),\r\n" );
document.write( "equal to what's in the \"DISTANCE returning\" box,\r\n" );
document.write( "just below it, namely, 250t:\r\n" );
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document.write( "     200(t+1) = 250t\r\n" );
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document.write( "Then we solve that equation and get t=4\r\n" );
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document.write( "But the question is: \r\n" );
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document.write( ">>...How far away is St. Paul?...<<\r\n" );
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document.write( "It doesn't ask for the time.  It asks \r\n" );
document.write( "for the distance. So we have to substitute\r\n" );
document.write( "t=4 into either the expression for the \r\n" );
document.write( "\"distance Going\" or the \"distance Returning\".  \r\n" );
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document.write( "Substituting t=4 into the expression\r\n" );
document.write( "for the \"distance Returning\":\r\n" );
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document.write( "    250t\r\n" );
document.write( "    250(4)\r\n" );
document.write( "    1000\r\n" );
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document.write( "So the \"distance Returning\" is 1000\r\n" );
document.write( "miles.  That's the answer.\r\n" );
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document.write( "As a check, we substitute t=4 into \r\n" );
document.write( "the expression for the \"distance Going\":\r\n" );
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document.write( "    200(t+1)\r\n" );
document.write( "    200(4+1)\r\n" );
document.write( "    200(5)\r\n" );
document.write( "    1000\r\n" );
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document.write( "So the distance Going is 1000\r\n" );
document.write( "miles also. So that checks, since the\r\n" );
document.write( "distance going should be the same as\r\n" );
document.write( "the distance returning.\r\n" );
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document.write( "Edwin
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