A bearing like that is technically an azimuth. It is turned clockwise from north or the positive y-axis right around the circle.

325-235=90, so you have a right triangle which is easy to work with.

Boat A travels 14*2.5=35 km

Boat B travels 18*2.5=45 km.

So you have two sides of length 35 and 45 and a 90 degree angle.

All you need is Pythagoras.