\[\boxed{\mathbf{3.}\mathbf{268}}\]
Пояснение.

Решение.


\[141 + 308 - 418 = 449 - 418 =\]
\[= 31\]


\[17 \cdot 9 = 153\]

\[153 - 13 = 140\]

\[34 - 24 = 10\]

\[17 \cdot 6 = 102\]
\[110 + 102 = 212\]
\[5 \cdot 64 = 320\]
\[400 - 320 = 80\]





\[707\ :7 = 101\]
\[8607 + 7605 = 16\ 212\]
\[16\ 212 + 101 = 16\ 313\]

\[5980 + 6620 = 12\ 600\]
\[5 \cdot 3 = 15\]

\[435 + 15 = 450\]