\[\boxed{\text{12.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[1.\ 25 \cdot 3 = 75.\]
\[2.\ 500 - 75 = 425.\]
\[3.\ 470 - 425 = 45.\ \]
\[1.\ 160\ :4 = 40.\]
\[2.\ 300 + 40 = 340.\]
\[3.\ 340\ :2 = (200 + 140)\ :2 =\]
\[= 100 + 70 = 170.\ \]