A= 20-6×3+1
=20-18+1
=2+1
=3
B= 4+3×2
=4+6
=10
C= 20-5×3
=20-15
=5
D= 8+2×5-7
=8+10-7
=18-7
=11
E= 12-8×15
=12-120
=-108
F= (7+4)×(2+1+6)÷3
=(11)×(3+6)÷3
=11×9÷3
=99÷3
=33
G= 7+9×3-4+10
=7+27-4+10
=34-4+10
=30+10
=40
H= 24×2-(7×3+8)÷1
=48-(21+8)÷1
=48-29÷1
=48-29
=19