document.write( "Question 1033437: the cost of petrol rises by 2 naira per litre. last week a motorist bought 25 litres at the old prices. this week she bought 20 litres at new price. altogether, the petrol cost 3640 naira. what was the old price for 1 litre \n" ); document.write( "
Algebra.Com's Answer #648073 by Theo(13342)\"\" \"About 
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let x = the old price.
\n" ); document.write( "then x + 2 = the new price.\r
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\n" ); document.write( "\n" ); document.write( "25 * x + 20 * (x+2) = 3640\r
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\n" ); document.write( "\n" ); document.write( "simplify to get 25 * x + 20 * x + 40 = 3640\r
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\n" ); document.write( "\n" ); document.write( "combine like terms to get 45 * x + 40 = 3640\r
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\n" ); document.write( "\n" ); document.write( "subtract 40 from both sides of the equation to get 45 * x = 3600\r
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\n" ); document.write( "\n" ); document.write( "divide both sides of the equation by 45 to get x = 80.\r
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\n" ); document.write( "\n" ); document.write( "the old price per liter is 80.
\n" ); document.write( "the new price per liter is 82.\r
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\n" ); document.write( "\n" ); document.write( "25 * 80 + 20 * 82 = 3640.\r
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\n" ); document.write( "\n" ); document.write( "old price per liter is 80 naira.\r
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