This is inspired by/alternative to Olba12's nice answer:
$$\begin{align} 30 &= 10 + 10 + 10\\ &= (11 - 1) + (11 - 1) + (9 - 1)\\ &= 31 - 3\\ &= 31 - 2 - 1\\ &= 29 - 1 \end{align}$$
Hence: $29 - 1 = 30$.
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Masked Man
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