



 
Hi Jessica. You want to know the rate of the current, so let's call it R. On the way to the city (upstream), the boat is fighting the current, so its effective speed is R12. On the way back (downstream), the boat is going with the current, so its effective speed is R+12. The total time is 3 hours, which equals the sum of the time going to the city and the time returning: 3 = [ 10 / (R12) ] + [ 10 / (R+12) ] Solve for R. Cheers,  


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