\[\boxed{\text{Занимательные}\text{\ }\text{рамки}\text{\ }\text{на}\text{\ }\text{стр}\text{.\ 67}}\]
\[1)\ 900 - (350 + 190) =\]
\[= 900 - 540 = 360\]
\[900 - (420 + 190) =\]
\[= 900 - 610 = 290\]
\[900 - (420 + 350) =\]
\[= 90 - 770 = 130\]
\[2)\ 320 - (60 + 70) =\]
\[= 320 - 130 = 190\]
\[320 - (90 + 60) = 320 - 150 =\]
\[= 170\]
\[320 - (90 + 70) = 320 - 160 =\]
\[= 160\]