A fish swim 8 miles downstream in two hours he return upstre

A fish swim 8 miles downstream in two hours. he return upstream in 14 hours. how fast does the fish swim in still water ?

c = speed of the current
r = speed of the fish
use d = rt
8 = (r+c)*2 downstream
8 = (r-c)*14 upstream
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2r + 2c = 8 --> 14r + 14c = 56
14r-14c = 8
14r+14c = 56
------------- Add the equations
28r = 64
r = 16/7 mph