Can someone explain this to me please

Answer: Choice B
Explanation:
Everywhere you see an x, replace it with a+2.
[tex]f(x) = 3(x+5)+\frac{4}{x}\\\\f(a+2) = 3(a+2+5)+\frac{4}{a+2}\\\\f(a+2) = 3(a+7)+\frac{4}{a+2}\\\\[/tex]