Question 1073328
r, the speed of the train going from New York to Boston

<pre>
                     SPEED      TIME      DISTANCE
Boston to NY        2r-10        2        2(2r-10)
NY to Boston          r          2        2r
Total                                     220
</pre>


The only unknown is r.  Distance summation gives {{{highlight_green(2(2r-10)+2r=220)}}}, and solving this gives {{{highlight_green(r=40)}}}.


To find how far from Boston the two trains meet, simply use {{{220-2r}}}
{{{220-2*40}}}
{{{220-80}}}
{{{highlight(140)}}}