\[Страница\ 56\]
\[\boxed{\mathbf{83.}}\]
\[1)\ 40 - 28 = 40 - 20 - 8 =\]
\[= 20 - 8 = 12\]
\[70 - 56 = 70 - 50 - 6 =\]
\[= 20 - 6 = 14\]
\[2)\ 50 - 37 = 13\]
\[40 - 15 = 25\]
\[70 - 23 = 47\]
\[60 - 43 = 17\]
\[70 - 32 = 38\]
\[80 - 54 = 26\]
\[\boxed{\mathbf{84.}}\]
\[56 - 30 - 7 = 26 - 7 =\]
\[= 19\ (р.) - стоил\ альбом.\]
\[Ответ:19\ рублей.\]
\[\boxed{\mathbf{85.}}\]
\[8 + 7 = 15 - 9 = 6 + 8 =\]
\[= 14 - 8 = 6 - 1 = 5\]