Aiko stands 5 m from a tree. at that distance, the angle of elevation from the ground to the top of the tree is 80°. approximately how tall is the tree?

This is the concept of trigonometry, the height of the tree will be given by:
tan theta=[opposite]/[adjacent]
theta=80
height=h
adjacent=5 m
hence;
tan80=h/5
hence;
h=5tan80
h=28.36 m

If you divide 0.1 and 0.6 you wii get 0.166666 which rounds to .167 which is answer b