Условие:

Назови результаты.
50 + 40
60 − 10
60 + 10
80 − 30
20 + 20
30 + 60
90 − 80
30 + 30
100 − 10
100 − 50
40 + 60
10 + 10

Результаты: 90, 50, 70, 50, 40, 90, 10, 60, 90, 50, 80, 20.
50 + 40 = 90
60 − 10 = 50
60 + 10 = 70
80 − 30 = 50
20 + 20 = 40
30 + 60 = 90
90 − 80 = 10
30 + 30 = 60
100 − 10 = 90
100 − 50 = 50
40 + 40 = 80
10 + 10 = 20
Вычисления:
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}50\\ 40\end{array}}\\ \begin{array}{r}90\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}60\\ 10\end{array}}\\ \begin{array}{r}50\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}60\\ 10\end{array}}\\ \begin{array}{r}70\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}80\\ 30\end{array}}\\ \begin{array}{r}50\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}20\\ 20\end{array}}\\ \begin{array}{r}40\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}30\\ 60\end{array}}\\ \begin{array}{r}90\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}90\\ 80\end{array}}\\ \begin{array}{r}10\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}30\\ 30\end{array}}\\ \begin{array}{r}60\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}100\\ 10\end{array}}\\ \begin{array}{r}90\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}100\\ 50\end{array}}\\ \begin{array}{r}50\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}40\\ 40\end{array}}\\ \begin{array}{r}80\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}10\\ 10\end{array}}\\ \begin{array}{r}20\end{array}\end{array}$