a) Đặt tính rồi tính ta có:
\(\begin{array}{*{20}{c}}{ + \begin{array}{*{20}{c}}{12}\\{\,\,8}\end{array}}\\\hline{\,\,\,20}\end{array}\) \(\begin{array}{*{20}{c}}{ + \begin{array}{*{20}{c}}{33}\\{\,\,7}\end{array}}\\\hline{\,\,\,40}\end{array}\)
\(\begin{array}{*{20}{c}}{ + \begin{array}{*{20}{c}}{65}\\{\,\,5}\end{array}}\\\hline{\,\,\,70}\end{array}\) \(\begin{array}{*{20}{c}}{ + \begin{array}{*{20}{c}}{84}\\{\,\,6}\end{array}}\\\hline{\,\,\,90}\end{array}\)
Vậy ta có kết quả như sau:
b)
\(\begin{array}{*{20}{c}}{ + \begin{array}{*{20}{c}}{35}\\{\,\,\,5}\end{array}}\\\hline{\,\,\,\,40}\end{array}\) \(\begin{array}{*{20}{c}}{ + \begin{array}{*{20}{c}}{69}\\{\,\,\,4}\end{array}}\\\hline{\,\,\,\,73}\end{array}\)
\(\begin{array}{*{20}{c}}{ + \begin{array}{*{20}{c}}{19}\\{\,\,\,3}\end{array}}\\\hline{\,\,\,\,22}\end{array}\) \(\begin{array}{*{20}{c}}{ + \begin{array}{*{20}{c}}{29}\\{\,\,\,6}\end{array}}\\\hline{\,\,\,\,35}\end{array}\)