Question 1073575
{{{N}}}= the number of escalator steps visible
As Jess was briskly walking up the escalator,
{{{N-42}}} of the originally visible steps disappeared at the top.
On the second trip up the escalator,
{{{N-24}}} steps were eaten up by the top platform.
Since the escalator moves at the same rate all the time,
the first trip took
{{{(N-42)/(N-24)}}} times as long as the second trip.
If Jess had been walking at the same leisurely pace,
Jess would have taken only {{{42/2=21}}} steps on the first trip.
That means that the first trip took
{{{21/24=7/8}}} as long as the second trip.
So,
{{{(N-42)/(N-24)=7/8}}}
{{{8(N-42)=7(N-24)}}}
{{{8N-8*42=7N-7*24}}}
{{{8N-8*7*6=7N-7*6*4}}}
{{{8N-7N=7*6(8-4)}}}
{{{N=42*4}}}
{{{highlight(N=168)}}}