§ Задание 90
\[\boxed{\mathbf{2}\mathbf{.}\mathbf{90}}\]
\[\textbf{а)}\ 50 \cdot 40 = 2000\]
\[\textbf{б)}\ 3000 \cdot 40 = 120\ 000\]
\[\boxed{\mathbf{2}\mathbf{.}\mathbf{90}}\]
\[\textbf{а)}\ 50 \cdot 40 = 2000\]
\[\textbf{б)}\ 3000 \cdot 40 = 120\ 000\]