\[\boxed{\mathbf{3.}\mathbf{248}}\]
Пояснение.
Решение.
\[\textbf{а)}\ (40 - 3) \cdot 5 = 40 \cdot 5 - 3 \cdot 5 =\]
\[= 200 - 15 = 185\]
\[\textbf{б)}\ 6 \cdot (80 - 2) = 6 \cdot 80 - 6 \cdot 2 =\]
\[= 480 - 12 = 468\]
\[\textbf{в)}\ 95 \cdot 317 - 85 \cdot 317 =\]
\[= 317 \cdot (95 - 85) = 317 \cdot 10 =\]
\[= 3170\]
\[\textbf{г)}\ 87 \cdot 316 - 87 \cdot 306 =\]
\[= 87 \cdot (316 - 306) = 87 \cdot 10 =\]
\[= 870\]