Step 1 :To solve for $x$ in the equation $\log _{5}(-2 x+5)=2$, we can use the property of logarithms that says $a = b^c$ is equivalent to $\log_b(a) = c$. So, we can rewrite the equation as $-2x + 5 = 5^2$.
Step 2 :Then, we can solve for $x$ by subtracting 5 from both sides of the equation and then dividing by -2.
Step 3 :The solution to the equation is $x = -10$.
Step 4 :Final Answer: $x = \boxed{-10}$