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MMO 055 Moscow MO 1940 days a raft floats the river

Source:

July 18, 2019
timealgebra

Problem Statement

It takes a steamer 55 days to go from Gorky to Astrakhan downstream the Volga river and 77 days upstream from Astrakhan to Gorky. How long will it take for a raft to float downstream from Gorky to Astrakhan?