Question 1075663
r, speed if no current
c, speed of the current

{{{system(r+c=55/(1&5/6),r-c=55/(3&2/3))}}}


{{{system(r+c=55/(11/6),r-c=55/(11/3))}}}


{{{system(r+c=30,r-c=15)}}}


{{{2c=15}}} by Elimination Method.

{{{highlight(c=7&1/2)}}}