document.write( "Question 908325: it takes bob 10 hours to clean his room. It takes his mom 5 hours to clean his room. If bob starts cleaning at 1 pm and his mother starts helping at 2pm at what time will bob's room be clean? \n" ); document.write( "
Algebra.Com's Answer #550969 by josmiceli(19441)\"\" \"About 
You can put this solution on YOUR website!
From 1 PM to 2 PM is 1 hr
\n" ); document.write( "------------------------
\n" ); document.write( "Bob's rate of cleaning is:
\n" ); document.write( "( 1 room ) / ( 10 hrs ) = \"+1%2F10+\"
\n" ); document.write( "--------------------
\n" ); document.write( "The fraction of the room cleaned by
\n" ); document.write( "Bob in \"+1+\" hr is:
\n" ); document.write( "\"+1%2A%28+1%2F10+%29+=+1%2F10+\" of the room
\n" ); document.write( "-------------------------------
\n" ); document.write( "That means there is \"+9%2F10+\" of the
\n" ); document.write( "room left to clean
\n" ); document.write( "-----------------
\n" ); document.write( "Add Bob's rate and his Mom's rate to
\n" ); document.write( "get their rate working together:
\n" ); document.write( "Let \"+t+\" = time in hrs for them to
\n" ); document.write( "finish working together
\n" ); document.write( "\"+1%2F10+%2B+1%2F5+=+%28%28+9%2F10%29%29+%2F+t+\"
\n" ); document.write( "Multiply both sides by \"+10t+\"
\n" ); document.write( "\"+t+%2B+2t+=+9+\"
\n" ); document.write( "\"+3t+=+9+\"
\n" ); document.write( "\"+t+=+3+\"
\n" ); document.write( "-------------
\n" ); document.write( "3 hrs after 2 PM is 5 PM
\n" ); document.write( "They will finish cleaning the room at 5 PM\r
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );