<PRE><B>Question 1184777</B>
This is much like another one solved recently.


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Anthony speed, r-13
Benjamin speed, r


They go opposite directions starting same time, so speeds are added.
Their speed of separation from starting place,  {{{r+r-13=2r-13}}}.


They become   791.7 miles apart after 8.7 hours.

{{{highlight_green(8.7(2r-13)=791.7)}}}.
Solve.
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