Question 729825
Rate is units of trenches per day.  Find the rate of 1 man.  One man is 1/3 of three men.  His rate is therefore {{{1/3}}} of {{{6/4}}} trenches per day.  This one-man rate is {{{(6/4)*(1/3)=1/2}}} trench per day.


Now you have rate*time=trenches.  For 4 men doing this work, {{{4*(1/2)*t=24}}}, where {{{t}}} is how many days for four men to dig 24 trenches.  Find {{{t}}}.