plz answer my question

Question

a river is 2 km wide and flows at 4km/h. a motorboat has a speed of 10 km/h in still water and heads out from one bank. a marina is directly across the river, on the opposite bank. if the motorboat heads directly toward the marina, how far downstream from the marina will be on the other bank? USING VECTOR COMPONENTS

. It takes 2/10 hours to cross the river. In that time, the boat drifts downstream 2/10*4 = 4/5 km. is that right

Now, if i want to find the heading needed to get straight across the river, then i need some vectors. but how am i support to do it?