§ Задание 4
\[\boxed{\mathbf{4.}}\]
\[40 + 20 = 60\]
\[50 + 20 = 70\]
\[20 + 30 = 50\]
\[30 + 50 = 80\]
\[30 + 40 = 70\]
\[60 + 20 = 80\]
\[40 + 60 = 100\]
\[50 + 50 = 100\]
\[\boxed{\mathbf{4.}}\]
\[40 + 20 = 60\]
\[50 + 20 = 70\]
\[20 + 30 = 50\]
\[30 + 50 = 80\]
\[30 + 40 = 70\]
\[60 + 20 = 80\]
\[40 + 60 = 100\]
\[50 + 50 = 100\]