Frame of reference question. Polar co-ordinates

A lighthouse keeper spots a ship sailing away from the shore. She marks the bearing from North to the ship as =24 degrees and estimates the distance to the ship as 2.4km. The captain of the ship notes the ship is heading = 30 degrees from north.

If the captain similarly estimates the distance to the lighthouse is 2.4km what are the **polar coordinates** of the lighthouse in the ships frame of reference?

ok so obviously r= 2.4 but for the angle i keep getting 186 degrees but that's wrong. Can someone explain to me how to get the angle?

Re: Frame of reference question. Polar co-ordinates