(a). The displacement is 3.6km.
(b). Average velocity is 2 km/hour
(a). A diagram is attached below which describe situation of question.
In diagram OB represent the displacement.
In right triangle OAB,
[tex](OB)^{2}=(OA)^{2}+(AB)^{2}\\ \\ OB^{2}=2^{2}+3^{2}=4+9=13\\ \\ OB=\sqrt{13}=3.6Km[/tex]
(b). Average velocity is given as,
[tex]v=\frac{Distance}{time}=\frac{2+3}{2.5} =5/2.5=2km/h[/tex]
Learn more about Displacement and Average velocity here:
https://brainly.com/question/862972
