How can you show that two objects are proportional with a table

What is the equation of the line shown in this graph?

The first-serve percentage of a tennis player in a match is normally distributed with a standard deviation of 4.3%. if a sample of 15 random matches of the player is taken, the mean first-serve percentage is found to be 26.4%. what is the margin of error of the sample mean? a. 0.086% b. 0.533% c. 1.11% d. 2.22%

F(x) = 1/x g(x)=x-4 can you evaluate (g*f)(0) ? why or why not?