How do I answer this

5. (25 pts) A 1840-kg truck moving North at 15.4 m/s collides with a 855-kg car moving 23.3 m/s West. The car and truck stick together after the collision. Find the magnitude and direction of their final velocity. (Hint 1: this is a 2-D problem.) (Hint 2: compass directions are like this:) North