1.1+2+3+4+……+100=50502.x+……+(x+9)=75，（2x+9）*10/2=75,x=3
1。直接按规律代入得:1+2+3+...+100=101*50=50502.还是代入得：x+(x+1)+(x+2)+...+(x+9)=10x+(1+9)*9/2=75x=3
Sorry, you write that I do not understand.
