看谁算得又对又快。
(1)78-50-9= (2)72-2-30=
(3)35+6+40= (4)47+9-20=
(5)17+3+15= (6)75-50+14=
(7)49-9-30= (8)28+20+2=
(9)99-20+6= (10)100-30-7=
(11)16+15-7= (12)70-30+33=
(13)85-6-19= (14)6+24+30=
(15)75-20-30= (16)62-5+7=
(17)64-6-40= (18)18+18-20=
(19)85+8-12= (20)75-15-20=