a) 4+6×(9-2×3)=
=4+6×(9-6)
=4+6×3
=4+18
=22
b) 16+2×(22-21:7)=
=16+2×(22-3)
=16+2×19
=16+38
=54
c)18:3+5×[11+5×(23-48:12)]=
=6+5×[11+5×(23-2)]
=6+5×(11+5×21)
=6+5×(11+105)
=6+5×116
=6+580
=586
d)10-9+8×{[7-(6+5-4)]+3-(2+1)}=
=10-9+8×{[7-(11-4)]+3-3}
=10-9+8×[(7-7)+3-3]
=10-9+8×(0+3-3)
=10-9+8×0
=10-9+0
=1+0
=1