1) 900 - 450 : 45 x 2 + 7= 2) (-3500) : (-50) + 12 x -3500 + 750= 3) 750 x 16 - 4500 : (-30) + 2.150=

1) 900 - 450 : 45 x 2 + 7=900-10x2+7
=900-20+7
=880+7
=887
2) (-3500):(-50)+12x-3500+750
=70+12x-3500+750
=70+(-42000)+750
=41930+750
=42680
3) 750 x 16 - 4500 : (-30) + 2.150
=12000-4500:(-30)+2150
=12000+150+2150
=12150+2150
=14300