Question

a river flows east at 3.0 m/s . a boat can go at 5.m/s relative to the water .what direction should the boat aim to travel from a point on the cast bank to a position directly west on the west bank?

Answer 1

You have mangled the question. If the river flows east, it has a north and south bank, not an east and west bank! So I shall assume a direction south to north. You can fix it if you need to.

draw a diagram of the velocity vectors
the direction is NθW where
sinθ = 3/5