\[\boxed{\mathbf{2.}\mathbf{213.ОК\ ГДЗ - домашка\ на\ }5}\]
\[\textbf{а)}\ 50 + 40 = 90\ :30 = 3 \cdot 50 =\]
\[= 150 - 100 = 50\]
\[\textbf{б)}\ 30 + 70 = 100\ :10 =\]
\[= 10 \cdot 15 = 150 - 150 = 0\]
\[\textbf{в)}\ 100 - 70 = 30 \cdot 3 =\]
\[= 90 - 18 = 72\ :36 = 2\]
\[\textbf{г)}\ 100 - 80 = 20\ :4 =\]
\[= 5 \cdot 14 = 70 - 67 = 3\]
\[\textbf{д)}\ 67 - 23 = 44\ :11 =\]
\[= 4 \cdot 25 = 100 - 19 = 81\]