document.write( "Question 730880: Jake can cut and split a cord of firewood in 6 fewer hours than Steve. When they work together, it takes them 4 hours. How long would it take each of them to do the job alone?
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Algebra.Com's Answer #446892 by jim_thompson5910(35256)![]() ![]() ![]() You can put this solution on YOUR website! Let \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = number of hours it takes Jake to do the job if he worked alone\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y = number of hours it takes Steve to do the job if he worked alone\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "We are told that \"Jake can cut and split a cord of firewood in 6 fewer hours than Steve\", so\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = y - 6\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-------------------------------------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "\"When they work together, it takes them 4 hours\", we can construct this equation\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "1/x + 1/y = 1/4\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "4xy(1/x) + 4xy(1/y) = 4xy(1/4) ... multiply EVERY term by the LCD 4xy to clear out the fractions\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "4y + 4x = xy\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "4y + 4(y-6) = (y-6)y ... plug in x = y-6\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "4y + 4(y-6) = (y-6)y\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "4y + 4y - 24 = y^2-6y\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "8y - 24 = y^2-6y\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "0 = y^2-6y-8y+24\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "0 = y^2-14y+24\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y^2-14y+24 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(y-12)(y-2) = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y-12 = 0 or y-2 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y = 12 or y = 2\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So the possible solutions for y are\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y = 12 or y = 2\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If y = 2, then \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = y - 6\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = 2 - 6\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = -4\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So y CANNOT be 2 because this makes x a negative number.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So toss out y = 2 as a solution\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If y = 12, then\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = y - 6\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = 12 - 6\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = 6\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So if y = 12, then x = 6\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Therefore, \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Jake can do the job in 6 hours if he worked alone. \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Steve can do the job in 12 hours if he worked alone. \n" ); document.write( " |