Question 825890
The way I read it, {{{ 88*3 = 264 }}} is
the length of the tunnel because 3 sec
is the time to go from entrance to exit
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The whole train takes {{{ 3 + 30 = 33 }}}
sec to get all the way through
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{{{ 33 }}} sec is {{{ 33/3 = 11 }}} times 
the length of the tunnel
If {{{ x }}} is the length of the train,
{{{ x = 11*264 }}}
{{{ x = 2904 }}}
The train is 2,904 ft long
You might want a 2nd opinion, but this
is how I see it