Đặt tính rồi tính: a) 8 phút 20 giây + 2 phút 10 giây

a)

\[\begin{array}{l} + \begin{array}{*{20}{c}}{\,\,\,8\,\,phu\`u t\,\,20\,\,gia\^a y}\\{\underline {\,\,2\,\,phu\`u t\,\,10\,\,gia\^a y} }\end{array}\\\,\,\,\,10\,\,phu\`u t\,\,30\,\,gia\^a y\end{array}\]

b)

\[\begin{array}{l} - \begin{array}{*{20}{c}}{\,\,3\,\,gi\^o {\o}\,\,\,15\,\,phu\`u t\,\,}\\{\underline {\,\,1\,\,gi\^o {\o}\,\,\,10\,\,phu\`u t\,\,} }\end{array}\\\,\,\,\,\,2\,\,gi\^o {\o}\,\,\,\,\,\,5\,\,phu\`u t\end{array}\]

c)

\[\begin{array}{l} \times \begin{array}{*{20}{c}}{\,\,2\,\,gi\^o {\o}\,\,\,25\,\,phu\`u t\,\,}\\{\underline {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,3\,\,\,\,\,\,\,\,\,\,\,\,\,\,} }\end{array}\\\,\,\,\,\,6\,\,gi\^o {\o}\,\,\,75\,\,phu\`u t\,\, = \,\,7\,\,gi\^o {\o}\,\,15\,\,phu\`u t\end{array}\]

d) 10  giôø  20  phuùt10  giôø ¯                   52  giôø  4  phuùt                  20  phuùt                  20  phuùt¯                      0