document.write( "Question 151442: I'm having some trouble solving these problems please help me.\r
\n" ); document.write( "\n" ); document.write( "Use algebraic techniques to solve rate problems and percent problems:\r
\n" ); document.write( "\n" ); document.write( "1.) Five tables and eight chairs cost $115; three tables and five chairs cost $70. Determine the cost of each table and each chair?\r
\n" ); document.write( "\n" ); document.write( "2.)A merchant sold his entire stock of shirts and ties for $1000, the shirts being priced at 3 for $10 and the ties at $2 each. If he sold 1/2 of the shirts and 2/3 of the ties he would have collected $600. How many of each kind did he sell?\r
\n" ); document.write( "\n" ); document.write( "3.)Determine the speed of a motorboat in still water and the speed of the river current, if it takes 3 hr to travel a distance of 45 mi upstream and 2 hr to travel 50 mi downstream?\r
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\n" ); document.write( "\n" ); document.write( "Please and thank you
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Algebra.Com's Answer #111332 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
1.) Five tables and eight chairs cost $115; three tables and five chairs cost $70. Determine the cost of each table and each chair?
\n" ); document.write( ":
\n" ); document.write( "Let x = cost of tables; let y = cost of chairs
\n" ); document.write( "Write an equation for each statement:
\n" ); document.write( "\"Five tables and eight chairs cost $115;\"
\n" ); document.write( "5x + 8y = 115
\n" ); document.write( "\"three tables and five chairs cost $70.\"
\n" ); document.write( "3x + 5y = 70
\n" ); document.write( "Use elimination here, Multiply the 1st equation by 3, the 2nd equation by 5
\n" ); document.write( "15x + 25y = 350
\n" ); document.write( "15x + 24y = 345
\n" ); document.write( "-------------------subtraction eliminates x, find y
\n" ); document.write( "0x + 1y = 5
\n" ); document.write( "y = $5 is cost of one chair
\n" ); document.write( ":
\n" ); document.write( "Find x using the 1st equation:
\n" ); document.write( "5x + 8(5) = 115
\n" ); document.write( "5x + 40 = 115
\n" ); document.write( "5x = 115 - 40
\n" ); document.write( "5x = 75
\n" ); document.write( "x = \"75%2F5\"
\n" ); document.write( "x = $15 is cost of one table
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\n" ); document.write( "Check solutions in 2nd equation
\n" ); document.write( "3(15) + 5(5) =
\n" ); document.write( "45 + 25 = 70
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\n" ); document.write( "2.)A merchant sold his entire stock of shirts and ties for $1000, the shirts being priced at 3 for $10 and the ties at $2 each. If he sold 1/2 of the shirts and 2/3 of the ties he would have collected $600. How many of each kind did he sell?
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\n" ); document.write( "Let x = no. of shirts sold
\n" ); document.write( "let y = no. of ties
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\n" ); document.write( "Write an equation for each statement:
\n" ); document.write( "\"A merchant sold his entire stock of shirts and ties for $1000, the shirts being priced at 3 for $10 and the ties at $2 each\"
\n" ); document.write( "10(\"x%2F3\") + 2y = 1000
\n" ); document.write( "\"%2810x%29%2F3\" + 2y = 1000
\n" ); document.write( "multiply equation by 3 to get rid of the denominator
\n" ); document.write( "10x + 6y = 3000; (1st equation)
\n" ); document.write( ":
\n" ); document.write( "\"If he had sold only 1/2 of the shirts and 2/3 of the ties he would have collected $600. How many of each kind did he sell?\"
\n" ); document.write( "\"1%2F2\"*\"%2810x%29%2F3\" + \"2%2F3\"*2y = 600
\n" ); document.write( "\"%2810x%29%2F6\" + \"%284y%29%2F3\" = 600
\n" ); document.write( "Reduce fraction
\n" ); document.write( "\"%285x%29%2F3\" + \"%284y%29%2F3\" = 600
\n" ); document.write( "Multiply equation by 3 to get rid of the denominator
\n" ); document.write( "5x + 4y = 1800
\n" ); document.write( ":
\n" ); document.write( "multiply above equation by 2 and subtract the 1st equation:
\n" ); document.write( "10x + 8y = 3600
\n" ); document.write( "10x + 6y = 3000
\n" ); document.write( "-----------------subtraction eliminates x
\n" ); document.write( "0x + 2y = 600
\n" ); document.write( "y = 300 ties sold
\n" ); document.write( ":
\n" ); document.write( "Find x, use eq: 10x + 6y = 3000
\n" ); document.write( "10x + 6(300) = 3000
\n" ); document.write( "10x + 1800 = 3000
\n" ); document.write( "10x = 3000 - 1800
\n" ); document.write( "10x = 3000 - 1800
\n" ); document.write( "10x = 1200
\n" ); document.write( "x = \"1200%2F10\"
\n" ); document.write( "x = 120 shirts sold
\n" ); document.write( ":
\n" ); document.write( "Check solution in
\n" ); document.write( "5x + 4y = 1800
\n" ); document.write( "5(120) + 4(300) =
\n" ); document.write( "600 + 1200 = 1800
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\n" ); document.write( ":
\n" ); document.write( "3.)Determine the speed of a motorboat in still water and the speed of the river current, if it takes 3 hr to travel a distance of 45 mi upstream and 2 hr to travel 50 mi downstream?
\n" ); document.write( ":
\n" ); document.write( "Let x = speed of boat in still water
\n" ); document.write( "Let y = speed of the current
\n" ); document.write( "then
\n" ); document.write( "(x+y) = speed with the current
\n" ); document.write( "and
\n" ); document.write( "(x-y) = speed against the current
\n" ); document.write( ":
\n" ); document.write( "Write a distance equation for each trip: Dist = time * speed
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\n" ); document.write( "2(x + y) = 50
\n" ); document.write( "3(x - y) = 45
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\n" ); document.write( "Simplify divide the 1st equation by 2 and the 2nd equation by 3; results:
\n" ); document.write( "x + y = 25
\n" ); document.write( "x - y = 15
\n" ); document.write( "------------addition eliminates y, find x
\n" ); document.write( "2x = 40
\n" ); document.write( "x = \"40%2F2\"
\n" ); document.write( "x = 20 mph speed of boat in still water
\n" ); document.write( ":
\n" ); document.write( "Find y using; x + y = 25
\n" ); document.write( "20 + y = 25
\n" ); document.write( "y = 25 - 20
\n" ); document.write( "y = 5 mph speed of the river
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check solutions in the 2nd original equation
\n" ); document.write( "3(x - y) = 45
\n" ); document.write( "3(20-5) = 45
\n" ); document.write( "3(15) = 45; confirms our solution
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