Brug Mix (reeks 1)

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\(21 + 24 = \ldots\)

\(\begin{align} & 21 + 24\\= & \color{green}{20} + \color{red}{1} + \color{green}{20} + \color{red}{4} \\= & \color{green}{40} + \color{red}{5} \\= & \color{red}{45} \end{align}\)