a) 3+3×[3+3:3×(3+3×3)]:15 =
3+3×[3+1×(3+9)]:15 =
3+3×[3+1×12]:15 =
3+3×[3+12]:15 =
3+3×15:15 =
3+45:15 =
3+3 = 9
b) 812-4×[6×(61-3600:12:30)]:9 =
812-4×[6×(61-10)]:9 =
812-4×[6×51]:9 =
812-4×306:9 =
812-1224:9 =
812-136 = 676
c) [214+240:(16-2×5)]×25-25:25 =
[214+240:(16-10)]×25-1 =
[214+240:6]×25-1 =
[214+40]×25-1 =
254×25-1 =
6350-1 = 6349
d) 90+7×[1614-12000:(18-10)]-16 =
90+7×[1614-12000:8]-16 =
74+7×[1614-1500] =
74+7×114 =
74+798 = 872
e) 44+8×[280:(37-1480:20:37)]:32-7 =
44+8×[280:(37-2)]:32-7 =
37+8×[280:35]:32 =
37+8×8:32 =
37+64:32 =
37+2 = 39
f) (18×8+56):[50×40:(220-2×60)] =
(144+56):[2000:(220-120)] =
200:[2000:100] =
200:20 = 10