document.write( "Question 1125126: One hundred gallons of 70% disinfectant is mixed with a certain amount of 90%
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Algebra.Com's Answer #741441 by ikleyn(52781) $\"\"$ $\"About$

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document.write( "Let x be the amount of the 90% disinfectant (in gallons).\r\n" );
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document.write( "Your equation is \r\n" );
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document.write( "    pure disinfectant + pure disinfectant = total pure disinfectant,     or\r\n" );
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document.write( "    0.7*100           + 0.9x              = 0.75*(100+x),        \r\n" );
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document.write( "    0.7*100           + 0.9x              = 0.75*100 + 0.75x\r\n" );
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document.write( "    0.9x - 0.75x = 0.75*100 - 0.7*100\r\n" );
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document.write( "    x =  = 33.333 gallons.\r\n" );
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document.write( "Answer.  33.333 gallons of the 90% disinfectant.\r\n" );
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document.write( "Check.   0.7*100 + 0.9*33.333 = 100 gallons of the pure disinfectant;\r\n" );
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document.write( "         0.75*(100+33.333) = 100 gallons of the pure disinfectant.   ! Correct !\r\n" );
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