document.write( "Question 92380: a faucet can fill a tub in 20 minutes, a drain can empty that same tub in 40 minutes if both the faucet and drain are open, how long will it take to fill the tub? \n" ); document.write( "
Algebra.Com's Answer #67202 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
a faucet can fill a tub in 20 minutes, a drain can empty that same tub in 40 minutes if both the faucet and drain are open, how long will it take to fill the tub?
\n" ); document.write( "---------
\n" ); document.write( "Faucet DATA:
\n" ); document.write( "Time = 20 min/job ; Rate = 1/20 job/min
\n" ); document.write( "--------------------
\n" ); document.write( "Drain DATA:
\n" ); document.write( "Time = 40 min/job ; Rate = 1/40 job/min
\n" ); document.write( "-----------------
\n" ); document.write( "Together DATA;
\n" ); document.write( "Time = x min/job ; Rate = 1/x job/min\r
\n" ); document.write( "\n" ); document.write( "-----------------
\n" ); document.write( "EQUATION:
\n" ); document.write( "rate fill - rate empty = rate together
\n" ); document.write( "1/20 - 1/40 = 1/x
\n" ); document.write( "Multiply thru by 40x to get:
\n" ); document.write( "2x-x = 40
\n" ); document.write( "x = 40 min (Time to fill if the faucet is open and the drain is open)
\n" ); document.write( "===========
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "
\n" );