Question 1043631
{{{k}}}= the length of the trail that Emily has walked (as percent of the total trail
{{{100-k}}}= the length of the trail that Emily has left to go (as percent of the total trail
{{{100}}} = the length of the trail (as percent of the total trail)

{{{10}}}= the length of the trail that Emily has left to go (in km)
{{{L}}}= the length of the trail (in km)
 
The ratios of total distance to distance left to go are
{{{L/10}}} and {{{100/(100-k)}}} .
Those expressions are the same ratio/fraction, calculated using different units, so
{{{L/10=100/(100-k)}}}---->{{{L=10(100/(100-k))}}}---->{{{L=highlight(1000/(100-k))}}}
If you are typing on one line, you would write it as {{{L="1000 / ( 100 - k )"}}} .