Question 1196109
Head Gardener, speed {{{2/x}}}
Assistant speed, {{{1/x}}}

The two together do the mowing work in {{{4/3}}} hours.


{{{(2/x+1/x)(4/3)=1}}}
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{{{3/x=3/4}}}


{{{highlight(x=4)}}}----------time needed for just the assistant to do the work.
Time for the head gardener alone,  {{{highlight(highlight(2))}}} hours.