=(18+2)+(16+4)+(14+6)+(12+8)+10
=20+20+20+20+10
=20x4+10
=80+10
=90
k cho tui đi mà
2+4+6+8+10+12+14+16+18
= ( 2 + 8 ) + ( 4 + 6 ) + ( 14 + 16 ) + ( 12 + 18 ) + 10
= 10 + 10 + 30 + 30 +10
= 90 .
=(2+18)+(4+16)+(6+14)+(8+12)+10
=20+20+20+20+10
=90
=(12+8)+(14+6)+(16+4)+(18+2)+10
=20+20+20+20+10
=90
=(2+18)+(4+16)+(6+14)+(8+12)+10
=20+20+20+20+10
=90
2+4+6+8+10+12+14+16+18
=(2+18)+(4+16)+(6+14)+(8+12)+10
=20+20+20+20+10
=90
=(2+18)+(4+16)+(6+14)+(8+12)+10 =20+20+20+20+10 =80+10 =90
2+4+6+8+10+12+14+16+18
= [18+2]+[16+4]+[6+14]+[12+8]+10
=20+20+20+20+10
=90