Answer:
7.5 km/h (2.1 m/s) due east
Explanation:
The average velocity of the person is given by:

where
d is the displacement
t is the time taken
In this problem,
d = 15 km is the displacement
t = 2.0 h is the time elapsed
so the average velocity is

and the direction is the same as the displacement (east).
We can also convert the velocity into SI units (m/s). We have:
d = 15 km = 15,000 m
t = 2.0 h * 3600 s/h = 7200 s

68.6m/s is the answer <span />
Some properties I know are
melting point<span>
, </span>
boiling point<span>
, and index of </span>
refraction<span>.</span>