Answer
:
All that is
necessary is to add the two distances
at which
they meet to
twice their difference.
Thus 720 + 400 + 640 = 1760 yards, or one mile,
which is the distance required.
Or, put another
way, three times the
first distance less the second distance will always give the answer,
only
the first distance should be more than twothirds of the second.
