The graph of g(x) is the graph of f(x)=5x+15 compressed horizontally by a factor of 1/5 . which equation describes the function g? a. g(x)=25x+75 b. g(x)=x+15 c. g(x)=x+3 d. g(x)=25x+15

We can easily get the function of g when looking at the graph, but sadly you don't attached any graph in this question.
f(x) = 5x + 15
y = 5x + 15  (f(x) is also equal to y)
0 = 5x + 15  (change the y into 0)
5x = 15 
x = 15/3 
x = 3 or 0 = x + 3

so basically g(x) = x +3

The answer is C. g(x) x + 3