Brug Mix (reeks 1)

Reken uit

\(20 + 23 = \ldots\)

\(\begin{align} & 20 + 23\\= &20 + \color{green}{20} + \color{red}{3} \\= & \color{green}{40} + \color{red}{3} \\= & \color{red}{43} \end{align}\)