Explain how the diameter and circumference are related?

Let f(x) = x+3 and g(x) = 1/x the graph of (fog)(x) is shown below what is the range of (fog)(x)?

Tod does not have any cookies. david gives jeff 8 cookies. then he splits half of the cookies he has left with tod. david let’s c represent the number of cookies that he starts with. he finds the number of cookies that tod has is 1/2 the difference of c and 8. write an expression to represent the number of cookies that tod has.

Could somebody me with this radical simplification?