=36*69-70*35=(35*69+69)-(35*69+35)=69-35=34
原式=[(1+12+23)x(12+23)+(1+12+23)x34]-[(1+12+23)x(12+23)+34x(12+23)] =(1+12+23)x34-(12+23)x34=1x34=34
