How do you use an exponent to represent a number such as 16

Astick 2 m long is placed vertically at point b. the top of the stick is in line with the top of a tree as seen from point a, which is 3 m from the stick and 30 m from the tree. how tall is the tree?

Bring the fraction a/a-4 to a denominator of 16-a^2

The functions f(x) and g(x) are shown in the graph f(x)=x^2 what is g(x) ?