document.write( "Question 162695: Solve using addition/elimination.\r
\n" ); document.write( "\n" ); document.write( "1.8x-2y=.9
\n" ); document.write( ".04x+.18y=.15 \n" ); document.write( "

Algebra.Com's Answer #119931 by Alan3354(69443) $\"\"$ $\"About$

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Solve using addition/elimination.
\n" ); document.write( "1.8x-2y=.9
\n" ); document.write( ".04x+.18y=.15
\n" ); document.write( "-------------
\n" ); document.write( "Multiply the 2nd eqn by 45
\n" ); document.write( "1.8x + 8.1y = 6.75
\n" ); document.write( "Subtract from eqn 1
\n" ); document.write( "0x - 10.1y = -5.85
\n" ); document.write( "y = 5.85/10.1 = 585/1010 = 117/202
\n" ); document.write( "--------------
\n" ); document.write( "Sub into eqn 2
\n" ); document.write( ".04x + .18*117/202 = .15
\n" ); document.write( "4x + 18*117/202 = 15
\n" ); document.write( "4x + 1053/101 = 1515/101
\n" ); document.write( "4x = 462/101
\n" ); document.write( "x = 231/202
\n" ); document.write( "--------------
\n" ); document.write( "Check:
\n" ); document.write( "1.8x-2y=.9
\n" ); document.write( "1.8*231/202 - 2*117/202 =? .9
\n" ); document.write( "Divide by 9
\n" ); document.write( ".2*231/202 - 2*13/202 =? .1
\n" ); document.write( "46.2/202 - 26/202 =? .1
\n" ); document.write( "20.2/202 is .1, so it's correct \n" ); document.write( "

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