2 + 2 + 2 + 2 + 2 - 10 + 1 - 1 + 2 - 2 + 6 - 6 + 11 - 10 + 1 - 1
= 2 x 5 + 10 + 1 - 1 + 2 - 1 + 6 - 6 + 11 - 10 + 1 - 1
= 10 + 10 + 0 + 1 + 0 + 1 + 0
= 20 + 2
= 22
cộng trừ dần ta có 2+2+2+2+2-10+1-1+2-2+6-6+11-10+1-2=10-10+1-1+2-2+6-6+11-10+1-2=0+0+0+0+1+1-2=2-2=0
thế nhé^^