Frame of reference
avengefulghost,
Although you might have used a longer method, your answer is still correct. Assuming that E25S means 25 degrees S of east or 115 degrees then it is simply a case of breaking each vector into its components
Running x=4, y=0
Swimming x = 0.85, y = 1.81
Combined (Add X's and Y's) x = 3.15 , y = 1.81
Magnitude of the final velocity = SQRT(X^2+Y^2) = 3.64
Bearing of the final velocity (X = N) = ArcCos(3.15/3.64) = 29.88 degrees which is what you got.
The recipe is to break the components down into the x's and y's, add the x's and y's, use pythagoras to find the magnitude and then apply trigonometry to get the bearing. Bearings can be a bit tricky but normally the convention is to take it clockwise with zero being north unless you are told differently.
