It is proven, that for the first-countable space $X,$ nonisolated point $x_0$ from $X,$  or which the set $\{x_0\}$ is closed, and any bounded function $f: X → \mathbb{R},$ that is continuous for $x ≠ x_0,$ uniform distance $d(f,K_{x_0}(X))$ from function $f$ to space $K_{x_0}(X)$  of all quasi-continuous in the point $x_0$ functions $g: X → \mathbb{R}$ is half of the distance from  $f(x_0)$ to the cluster set $C(ḟ,x_0),$ where $ḟ = f|_{X \setminus \{x_0\}}$.

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