document.write( "Question 405292: office has an old copying machine and a new one. together it takes both machines 4 hours to copy all financial reports. alone it takes the old copier 15 hours longer than the new one to make all copies . how long will it take the new copying machine to make all the copies \n" ); document.write( "
Algebra.Com's Answer #286290 by stanbon(75887)![]() ![]() ![]() You can put this solution on YOUR website! office has an old copying machine and a new one. \n" ); document.write( "together it takes both machines 4 hours to copy all financial reports. \n" ); document.write( "alone it takes the old copier 15 hours longer than the new one to make all copies . \n" ); document.write( "how long will it take the new copying machine to make all the copies \n" ); document.write( "------------------------- \n" ); document.write( "New copier DATA: \n" ); document.write( "time = x hrs/job ; rate = 1/x job/hr \n" ); document.write( "----- \n" ); document.write( "Old copier DATA: \n" ); document.write( "time = (x+15) hrs/job ; rate = 1/(x+15)job/hr \n" ); document.write( "---- \n" ); document.write( "Together DATA: \n" ); document.write( "time = 4 hrs/job ; rate = 1/4 job/hr \n" ); document.write( "========================================== \n" ); document.write( "Equation: \n" ); document.write( "rate + rate = together rate \n" ); document.write( "1/x + 1/(x+15) = 1/4 \n" ); document.write( "Multiply thru by 4x(x+15) to get: \n" ); document.write( "4(x+15) + 4x = x(x+15) \n" ); document.write( "--- \n" ); document.write( "4x + 60 + 4x = x^2+15x \n" ); document.write( "--- \n" ); document.write( "x^2 + 7x - 60 = 0 \n" ); document.write( "x^2+12x-5x-60 = 0 \n" ); document.write( "x(x+12)-5(x+12) = 0 \n" ); document.write( "(x+12)(x-5) = 0 \n" ); document.write( "Positive solution: \n" ); document.write( "x = 5 hrs (time for the new machine) \n" ); document.write( "x+15 = 20 hrs (time for the old machine) \n" ); document.write( "================================== \n" ); document.write( "Cheers, \n" ); document.write( "Stan H. \n" ); document.write( " |