document.write( "Question 648334: You can paint a certain room in 7 hours. Your brother can do it in 4 hours. How long does it take the two of you working together?
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Algebra.Com's Answer #406646 by checkley79(3341)\"\" \"About 
You can put this solution on YOUR website!
1/7+1/4=1/X Find a common denominator (7*4=28)
\n" ); document.write( "4/28+7/28=1/x
\n" ); document.write( "11/28=1/x Cross multiply
\n" ); document.write( "11x=28*1
\n" ); document.write( "11x=28
\n" ); document.write( "x=28/11
\n" ); document.write( "x=2.55 Hours when they work together.
\n" ); document.write( "Proof:
\n" ); document.write( "1/7+1/4=1/2.55
\n" ); document.write( ".143+.25=.392
\n" ); document.write( ".393=.392\r
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