The hypotenuse has the length 25, one leg has the length 24 and therefore the second leg must be 7 (Pythagorean theorem)
Since you know all three sides of the triangle you can choose the trigonometric function you like. I'll take Cosine function:
The definition of speed is:
Plug in the values you already know:
that means you'll get:
I'm a little bit confused about the running speed of the man. You don't need this fact. If - and only if - you are asked to find the minimum time it takes to go from A to B by rowing and running, then, of course, my calculations are wrong.