Răspuns:
1)=215+270:[48:6+(54+28)] =390:3+[16×4+(3:16)]
=215+270:(48:6+82) =390:3+[16×4+(-8)]
=215+270:(8+82) =390:3+[64+(-8)]
=215+270:90 =390:3+56
=215+30 =130+56
=245 =186
2)a-57+(29×3×5-200)+602=865
a-57+(87×5-200)+602=865
a-57+(435-200)+602=865
a-57+235+602=865
a-57+235=865-602
a-57+235=263
a-57=263-235
a-57=28
a=28+57
a=85
3)a+49-(17×6×9-64)+318=443
a+49-(102×9-64)+318=443
a+49-(918-64)+318=443
a+49-854+318=443
a+49-854=443-318
a+49-854=125
a+49=125+854
a+49=979
a=979-49
a=930
