Đặt tính rồi tính: 34 + 45

34 + 45

$\begin{array}{l}+\underset{¯}{\begin{array}{l}34\\ 45\end{array}}\\ 79\end{array}$

7 + 22

$\begin{array}{l}+\underset{¯}{\begin{array}{l}7\\ 22\end{array}}\\ 29\end{array}$

67 – 6

$\begin{array}{l}-\underset{¯}{\begin{array}{l}67\\ 6\end{array}}\\ 61\end{array}$

48 – 20

$\begin{array}{l}-\underset{¯}{\begin{array}{l}48\\ 20\end{array}}\\ 28\end{array}$