PLEASE HELP!! WILL GIVE BRAINLIEST TO RIGHT ANSWER.

Answer:
[tex]f(x)=\sqrt{8-7}=\sqrt{1}=1[/tex]
Step-by-step explanation:
[tex]f(x)=\sqrt{x-7}\\\\f(x)=\sqrt{8-7}=\sqrt{1}=1[/tex]