We have the following function
[tex]f(x)=\frac{3}{x+2}-\sqrt{x-3}[/tex]
We want to know what is the value of f(x) when x is 19
[tex]f(19)=\frac{3}{19+2}-\sqrt{19-3}=1/7-4=\boxed{-27/7}[/tex]
If you have additional questions feel free to ask.
Hope this helps.