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put this solution on YOUR website!let s=salmon and c=current
upstream __ s-c=100m/20 min __ s-c=5m/min
downstream __ s+c=100m/8min __ s+c=12.5m/min
adding the two equations __ s-c+(s+c)=5+12.5 __ 2s=17.5 __ s=8.75m/min
substituting __ 8.75+c=12.5 __ c=3.75m/min