Minimum Number of Distinct Distances

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Given that the upper bound on the number of unit distances determined by n points in a real space is $ cn^\frac{4}{3} $

Give a lower bound on the min. number of unique distances.

I am really struggling with this, any thoughts appreciated. Thanks

Attempt 1:

I know that the total distances = $n^2$

Let

$$ T = Total \space Distance = n^2$$ $$ U = Unit \space Distance \le cn^\frac{4}{3} $$ $$ K = Distinct \space Distances $$

So, $\space $ T = U + K

$$ T - K \le cn^\frac{4}{3}$$ $$ n^2 - K \le cn^\frac{4}{3}$$

Therefore

$$ K \ge n^2(1-cn^\frac{2}{3}) $$

Is this correct? The big question is does the equation T = U + K hold?