6,29 дм − 14 см = 6,29 дм − 1,4 дм = 4,89
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}\mathrm{6,29}\\ \mathrm{1,40}\end{array}}\\ \begin{array}{r}\mathrm{4,89 }\end{array}\end{array}$

3,2 дм + 8 см = 3,2 дм + 0,8 дм = 4 дм
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}\mathrm{3,2}\\ \mathrm{0,8}\end{array}}\\ \begin{array}{r}\mathrm{4,0 }\end{array}\end{array}$

28 дм − 146 см = 28 дм − 14,6 дм = 13,4 дм
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}\mathrm{28,0}\\ \mathrm{14,6}\end{array}}\\ \begin{array}{r}\mathrm{13,4 }\end{array}\end{array}$

4 м 6 дм 5 см − 27 см 4 мм = 46,5 дм − 2,74 дм = 43,76 дм
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}\mathrm{46,50}\\ \mathrm{2,74}\end{array}}\\ \begin{array}{r}\mathrm{43,76 }\end{array}\end{array}$