Question 798635
A: width of river 300m
Tan = O/A
Target distance (O) upstream from point opposite (as if no current)
O= Tan 30 x 300
O=0.577 x 300=173.2m (upstream)

Cos=A/H
Distance travelled  (H) = 300/cos30 = 300/0.866 = 346.4m
Current will carry 4/5 of this distance = 277.1m (downstream)

Final landing -173.2+277.1 = 103.9m downstream