Thank you very much. Problem Solved. Please delete.
You will expect two equations and two unknowns, the unknowns being b and c. The upstream rate, taking LONGER time to accomplish, will be b-c, and the downstream rate will be b+c.
Start with the fundamental relationship, r*t=d, meaning "rate times time equals distance". Notice that the distance in both directions is the same 120 miles. But what is important is that you will make two equations.
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