document.write( "Question 257355: A Jet flew from Montreal to San-Francisco, a distance of 4000 km. On the return
\n" ); document.write( "trip the speed was increased by 300km/h. If the total trip took 13h, what was the speed from Montreal to San-Francisco? \n" ); document.write( "
Algebra.Com's Answer #189292 by drk(1908)\"\" \"About 
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This is an RTD problem. We can create a table based on the given information
\n" ); document.write( "JET . . . . . . rate . . . . . . . . . .time . . . . . . . . . . . . . . . . distance
\n" ); document.write( "m->s . . . . R . . . . . . . . . . . .4000/R . . . . . . . . . . .. . . .. 4000
\n" ); document.write( "s->m . . . . R + 300 . . . . . . .4000/(R + 300) . . . . . . .. . .4000
\n" ); document.write( "totals . . . . . . . . . . . .. . . . . .. . .13
\n" ); document.write( "So, from the table, we get
\n" ); document.write( "\"4000%2FR+%2B+4000%2F%28R%2B300%29+=+13\"
\n" ); document.write( "multiply by common denominator to get
\n" ); document.write( "\"4000%28R+%2B+300%29+%2B+4000R+=+13%28R%29%28R%2B300%29\"
\n" ); document.write( "simplifying, we get
\n" ); document.write( "\"8000R+%2B+1200000+=+13R%5E2+%2B+3900R\"
\n" ); document.write( "setting = 0, we get
\n" ); document.write( "\"13R%5E2+-+4100R+-+1200000+=+0\"
\n" ); document.write( "By quadratic, we get
\n" ); document.write( "R = 500 \n" ); document.write( "
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