document.write( "Question 1030071: It takes crew A 4 hours to paint a room. It takes crew B 5 hours to do the same job. How long will it take to paint the room with both crews working together. \n" ); document.write( "

Algebra.Com's Answer #644994 by josmiceli(19441) $\"\"$ $\"About$

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Crew A's rate of painting:
\n" ); document.write( "[ 1 room painted ] / [ 4 hrs ]
\n" ); document.write( "Crew B's rate of painting:
\n" ); document.write( "[ 1 room painted ] / [ 5 hrs ]
\n" ); document.write( "Let $\"+t+\"$ = time in hrs for A and B
\n" ); document.write( "to paint the room working together
\n" ); document.write( "------------------------------
\n" ); document.write( "Add their rates of painting to get
\n" ); document.write( "their rate of painting together
\n" ); document.write( " $\"+1%2F4+%2B+1%2F5+=+1%2Ft+\"$
\n" ); document.write( "Multiply both sides by $\"+20t+\"$
\n" ); document.write( " $\"++5t+%2B+4t+=+20+\"$
\n" ); document.write( " $\"+9t+=+20+\"$
\n" ); document.write( " $\"+t+=+2+%2B+2%2F9+\"$ hrs
\n" ); document.write( "Convert hrs to minutes
\n" ); document.write( " $\"+%282%2F9%29%2A60+=+13.333+\"$
\n" ); document.write( "--------------------
\n" ); document.write( "Working together they take
\n" ); document.write( "2 hrs 13.333 min to paint the room
\n" ); document.write( "-----------------
\n" ); document.write( "check:
\n" ); document.write( " $\"+1%2F4+%2B+1%2F5+=+1%2Ft+\"$
\n" ); document.write( " $\"+1%2F4+%2B+1%2F5+=+1%2F%2820%2F9%29+\"$
\n" ); document.write( " $\"+.25+%2B+.2+=+9%2F20+\"$
\n" ); document.write( " $\"+.45+=+.45+\"$
\n" ); document.write( "OK \n" ); document.write( "

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