Question 1124934
One job is "make 20000 aluminum cans".


Rate for old machine, r
Rate for new machine, 3r


Both machines together take 6 hours to do 1 job.
{{{4r*6=1}}}
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Question is asking for reciprocal of {{{3r}}}.
{{{4*2*3r=1}}}

{{{3r=1/8}}}


{{{1/(3r)=highlight(8)}}}---------------eight hours for new machine to do 1 job working alone.