Answer:
F(2x+3) = 12/(2x+3) +1/2
Explanation:
Put the argument of the function where the variable is. You can simplify if you want, but the original function definition is not simplified, so we assume it is not required.
F(x) = 12/x + 1/2
Put (2x+3) where x is:
F(2x+3) = 12/(2x+3) + 1/2