Yacht travels in a westerly direction at 4m.s-1 with a North East current at 2m.s-1 how far does it travel in 10 minutes and what angle relative to west?
<-4,0> + <√2,√2> = <-4+√2,√2>
so it travels 600*(20-8√2) m in the direction θ where
tanθ = √2/(-4+√2) = (4-√2)/7
You don't say whether you are measuring the angle in a clockwise of counter-clockwise direction, so I'll let you determine the sign.