document.write( "Question 319419: on monday, archie paid $3.40 for three doughnuts and two coffees. On tuesday he paid $3.60 for two doughnuts and three coffees. What was his bill for one doughnut and one coffee? \n" ); document.write( "
Algebra.Com's Answer #228733 by mananth(16946)\"\" \"About 
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on monday, archie paid $3.40 for three doughnuts and two coffees. On tuesday he paid $3.60 for two doughnuts and three coffees. What was his bill for one doughnut and one coffee?
\n" ); document.write( "..
\n" ); document.write( "let doughnut cost $x
\n" ); document.write( "coffee cost $y
\n" ); document.write( "..
\n" ); document.write( "Monday equation
\n" ); document.write( "1... 3x+2y=3.40
\n" ); document.write( "tuesday equation
\n" ); document.write( "2... 2x+3y=3.60
\n" ); document.write( "multiply eq1 by 2 and eq2 by3 & subtract
\n" ); document.write( "..
\n" ); document.write( "6x+4y-6x-6y=6.80-7.20
\n" ); document.write( "-2y=-0.40
\n" ); document.write( "y=0.2 cost of coffee
\n" ); document.write( "plug the value of y in eq1
\n" ); document.write( "3x+0.40=3.40
\n" ); document.write( "3x=3
\n" ); document.write( "x=1
\n" ); document.write( "Doughnut costs $1 & coffee costs 20 cents\r
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