Răspuns:
11/13
Explicație pas cu pas:
Formula lui Gauss spune ca 1+2+3+4+5+6+...+n=nx(n+1):2
axb+axc+axd+...+axn=ax(b+c+d+...+n)
A=11+22+33+...+110=11x(1+2+3+...+10)=11x[10x(10+1):2]=11x(10x11:2)=11x(110:2)= 11x55=605
B=13+26+39+...+130=13x(1+2+3+...+10)=13x[10x(10+1):2]=13x(10x11:2)=13x(110:2)= 13x55=715
A/B=605/715=11X55/13X55=11/13