document.write( "Question 847492: the total time taken to travel x km at 20 km/h and y km at 30 km/h is 3 hours . the time taken to travel x km at 40 km/h aand y km at 15 km/h is also 3 hours . find x and y \n" ); document.write( "

Algebra.Com's Answer #510479 by swincher4391(1107) $\"\"$ $\"About$

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x/20 + y/30 = 3
\n" ); document.write( "x/40 + y/15 = 3\r
\n" ); document.write( "\n" ); document.write( "multiply by 120 just to make everything nice.\r
\n" ); document.write( "\n" ); document.write( "6x + 4y = 360
\n" ); document.write( "3x + 8y = 360\r
\n" ); document.write( "\n" ); document.write( "Multiply the top equation by 2.\r
\n" ); document.write( "\n" ); document.write( "12x + 8y = 720
\n" ); document.write( "3x + 8y = 360
\n" ); document.write( "------------------
\n" ); document.write( "9x = 360\r
\n" ); document.write( "\n" ); document.write( "x = 40\r
\n" ); document.write( "\n" ); document.write( "Plug back in x = 40 where convenient\r
\n" ); document.write( "\n" ); document.write( "x/20 + y/30 = 3\r
\n" ); document.write( "\n" ); document.write( "40/20 + y/30 = 3\r
\n" ); document.write( "\n" ); document.write( "2 + y/30 = 3\r
\n" ); document.write( "\n" ); document.write( "y/30 = 1\r
\n" ); document.write( "\n" ); document.write( "y = 30\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So x = 40, y = 30\r
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