Because it demonstrates the relationship between a body and the forces acting upon it, and its motion in response to those forces. [Hope that helps]
You will get 20460000 as your answer which is broken down into, 2.046 x 10^7 as your number has to be between 1-10.
Wildlife researcher starts from a and then reaches b, he turns towards north 40 degree to move towards c.
Total displacement is ac
Total horizontal displacement = 4+4 cos40 =7.06 km
Total vertical displacement = 4 sin40 =2.57 km
Total displacement
= 7.51 km