Notice how the arrows on the mapping diagrams are paired with
the points on the graph of the functions.
You can move the point for $x$ on the mapping diagram to see how
the function value for the function $f(x) =2\cdot \exp_3(x-1) - 4$
changes both on the diagram and on the graph.
Uncheck the upper box to hide the graph and arrows on the diagram
for the function $f(x) =2\cdot \exp_3(x-1) - 4 = 2 \cdot 3^{x-1} -4 $.
Check the middle box to show the graph and arrows on the diagram
for the function $g(x) = 2 \cdot \log_3(x-1) - 4$.