India, March 16 -- David Wells, a British puzzler and popular mathematics writer, may not be as well-known as Henry Ernest Dudeney, but he has played a significant role in popularising puzzles nevertheless. He has written books with mathematical musings and puzzles from sources around the world, including the Bhakshali manuscript from India. Among his writings I have found the following puzzle, whose source I am not sure about. The solution he provides, however, is attributed to the National Council of Teachers of Mathematics, USA (1965).

#Puzzle 186.1

Four towns are located along a straight road. If we call them A, B, C and D, then AB is 5 km, BC is 8 km, and CD is 11 km.

Now there is a treasure located at some point on the road. Ther...