document.write( "Question 501017: slove the equations by substitution method
\n" ); document.write( "x+3y=10;2x+y=5 \n" ); document.write( "

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x+3y=10..........(1)
\n" ); document.write( "2x+y=5...........(2)
\n" ); document.write( "Take (1)
\n" ); document.write( "x+3y=10
\n" ); document.write( "x=10-3y
\n" ); document.write( "Substitute the value of x in (2), we have
\n" ); document.write( "2(10-3y)+y=5
\n" ); document.write( "20-6y+y=5
\n" ); document.write( "20-5y=5
\n" ); document.write( "-5y=5-20
\n" ); document.write( "-5y=-15
\n" ); document.write( "Divide by (-5)both sides of above equation
\n" ); document.write( "-5y/-5=-15/-5
\n" ); document.write( "y=3
\n" ); document.write( "Plug in the value of y in either equations (1) or (2)
\n" ); document.write( "We take (1)
\n" ); document.write( "x+3y=10..........(1)
\n" ); document.write( "x+3(3)=10
\n" ); document.write( "x+9=10
\n" ); document.write( "x=10-9
\n" ); document.write( "x=1\r
\n" ); document.write( "\n" ); document.write( "Solution set (1, 3)\r
\n" ); document.write( "\n" ); document.write( "Check
\n" ); document.write( "Put the value of x and y in (2)
\n" ); document.write( "2x+y=5...........(2)
\n" ); document.write( "2(1)+3=5
\n" ); document.write( "2+3=5
\n" ); document.write( "5=5 \n" ); document.write( "

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