\[\boxed{\text{Страница}\text{\ 61.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\boxed{196.}\]
\[(80 - 1) \cdot 7 = 80 \cdot 7 - 1 \cdot 7 =\]
\[= 560 - 7 = 553\]
\[(60 - 5) \cdot 8 = 60 \cdot 8 - 5 \cdot 8 =\]
\[= 480 - 40 = 440\]
\[(15 - 3) \cdot 2 = 15 \cdot 2 - 3 \cdot 2 =\]
\[= 30 - 6 = 24\]
\[\boxed{197.}\]
\[При\ любых\ значениях\ m,\ k\ и\ y,\ \]
\[кроме\ случаев,\ когда\ m < k,\]
\[\ верно\ равенство\ \]
\[(m - k) \cdot a = m \cdot a - k \cdot a\]
\[\boxed{198.}\]
\[79 \cdot 5 = (80 - 1) \cdot 5 = 395\]
\[35 \cdot 4 = (30 + 5) \cdot 4 = 140\]
\[78 \cdot 2 = (80 - 2) \cdot 2 = 156\]
\[150 \cdot 4 = (100 + 50) \cdot 4 = 600\]
\[\boxed{199.}\]
\[Номер\ квартиры:308.\]