Question 836046
Let {{{ d }}} = the total distance of the trip
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1st day:
They traveled {{{ (1/4)*d }}} leaving {{{ (3/4)*d }}} left
2nd day:
They traveled {{{ (1/2)*(3/4)*d }}}, leaving {{{ (1/2)*(3/4)*d }}}
3rd day:
They traveled {{{ (2/3)*(1/2)*(3/4)*d }}} leaving {{{ (1/3)*(1/2)*(3/4)*d }}} 
4th day:
They traveled {{{ (1/3)*(1/2)*(3/4)*d }}} 
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1st day:
{{{ (1/4)*d }}}
2nd day:
 {{{ (1/2)*(3/4)*d = (3/8)*d }}}
3rd day:
 {{{ (2/3)*(1/2)*(3/4)*d = (1/4)*d }}}
4th day:
{{{ (1/3)*(1/2)*(3/4)*d = (1/8)*d }}} 
They traveled the greatest distance on the 2nd day
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They traveled 12 km on the 3rd day
{{{ (1/4)*d = 12 }}}
{{{ d = 48 }}}
The whole trip was 48 km