document.write( "Question 980198: A can clean a room in 5 hours. After A worked alone for 2 hours, B joined him. Together they finished cleaned the room in an hour. How long would it take B to clean the room? \n" ); document.write( "
Algebra.Com's Answer #601403 by ikleyn(52787)\"\" \"About 
You can put this solution on YOUR website!
\r
\n" ); document.write( "\n" ); document.write( "Let  x  be the time  (in hours)  it takes for  B  to cleans the room.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Then  A  is cleaning  \"1%2F5\"  of the room area in  1  hour,  and  B  is cleaning  \"1%2Fx\"  of the room area in  1  hour.  Working together,  they are cleaning  \"1%2F5\" + \"1%2Fx\"  of the room in  1  hour. \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "From the condition, you have an equation \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"1%2F5\" + \"1%2Fx\" = \"3%2F5\",\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "since after  2  hours  A  just cleaned  \"2%2F5\"  of the room  and only  \"3%2F5\"  remained to clean.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Solve this equation step by step:\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "x + 5 = 3x,     (after multiplying both sides of the equation by  5x)\r
\n" ); document.write( "\n" ); document.write( "2x = 5,\r
\n" ); document.write( "\n" ); document.write( "x = 2.5.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Answer.  It will take  2\"1%2F2\"  hours for  B  to clean the room working alone. \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
\n" );