NeedHwkHelp

A fishing boat leaves port at 04:30 h in search of the day's catch. The boat travels 4.50km[E], then 2.50km[S], and finally 1.50km[W] before discovering a large school of fish on the sonar screen at 06:30h.

a) What is the boat's average speed.
b) Calculate the boat's average velocity.


Solved a) by finding the total distance (8.5Km) and dividing it by the total time(2h).
I got 4.25km/h for my a). Which I have solved.

Don't understand b) at all.. Please help the answer is 1.95km/h[S50E]