“On her return trip, the Proud Mary, going downriver at 11.4 m/s, is backed by a 4.0 m/s current what is her velocity relative to the fisherman on shore?” I don’t just want the answer I want to understand how to do it pls help !

Calculate the first and second velocities of the car with four washers attached to the pulley, using the formulas v1 = 0.25 m / t1 , and v2 = 0.25 m / (t2 – t1) where t1 and t2 are the average times the car took to reach the 0.25 and the 0.50 meter marks. record these velocities, to two decimal places, in table e.