Решебник по математике 6 класс Перова рабочая тетрадь | Страница 10

\[\boxed{\text{27.}}\]

\[200 \cdot 2 = 400\]

\[180 \cdot 2 = 360\]

\[420 \cdot 2 = 840\]

\[321 \cdot 2 = 643\]

\[243 \cdot 2 = 486\]

\[\boxed{\text{28.}}\]

\[480\ :4 = 120\]

\[800\ :4 = 200\]

\[240\ :4 = 60\]

\[420\ :4 = 105\]

\[\boxed{\text{29.}}\]

\[800\ :4 = 200\]

\[5 \cdot 80 = 400\]

\[630\ :7 = 90\]

\[8 \cdot 90 = 720\]

\[640\ :8 = 80\]

\[4 \cdot 90 = 360\]

\[540\ :9 = 60\]

\[6 \cdot 70 = 420\]

\[\boxed{\text{30.}}\]

\[1)\ (135 + 173)\ :2 =\]

\[= 308\ :2 = 154\]

\[2)\ (246 - 67) \cdot 4 = 716\]

\[3)\ 390 + 390\ :3 =\]

\[= 390 + 130 = 520\]