Question 411503
 Paul sells 180 bracelets in 30min and Jack sells 180 bracelets in 60min,selling together how many min will it take them to sell 180 bracelets ?
Sol'n:
work problem:
rate x time = 1
let x: the time spent to sold the 180 bracelets when are together
1/30+1/60=1/x
1/x=1/20
x=20 minutes ---answer

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