\begin{array}{rrr} \mathbf{9} & \mathbf{4} & \mathbf{20} \\ \mathbf{8} & \mathbf{5} & \mathbf{12} \\ \mathbf{7} & \mathbf{6} & \mathbf{\textcolor[rgb]{150,0,0}{?}} \\ \end{array}
? = Was ist die Antwort!
\begin{array}{rrrrlr} \mathbf{9} & & \qquad \mathbf{4} & & \qquad \mathbf{20} & \\ & -1 & & +1 & & -8 \\ \mathbf{8} & & \qquad \mathbf{5} & & \qquad \mathbf{12} \\ & -1 & & +1 & & -8 \\ \mathbf{7} & & \qquad \mathbf{6} & & \qquad \mathbf{\textcolor[rgb]{150,0,0}{12-8=4}} \\ \end{array}
\begin{array}{rrr} \mathbf{9} & \mathbf{4} & \mathbf{20} \\ \mathbf{8} & \mathbf{5} & \mathbf{12} \\ \mathbf{7} & \mathbf{6} & \mathbf{\textcolor[rgb]{150,0,0}{?}} \\ \end{array}
? = Was ist die Antwort!
\begin{array}{rrrrlr} \mathbf{9} & & \qquad \mathbf{4} & & \qquad \mathbf{20} & \\ & -1 & & +1 & & -8 \\ \mathbf{8} & & \qquad \mathbf{5} & & \qquad \mathbf{12} \\ & -1 & & +1 & & -8 \\ \mathbf{7} & & \qquad \mathbf{6} & & \qquad \mathbf{\textcolor[rgb]{150,0,0}{12-8=4}} \\ \end{array}