A=92-1/9-2/10-3/11-...-92/100
A=1+1+1+...+1-1/9-2/10-3/11-...-92/100 (1+1+1+...+1 Là 92 số 1)
A=(1-1/9)+(1-2/10)+(1-3/11)+...+(1-92/100)
A=8/9+8/10+8/11+...+8/100
A/8=1/9+1/10+1/11+...+1/100
A:8:5=A:40=1/45+1/50+1/55+...+1/500=B
=> A=40B
Vậy A/B=40B/B=40/1