(1又2/3+2又3/4+3又4/5+...97又98/99+98又99/100)/(3又1/3+5又2/4+7又3/5+.+195又97/99+197又99/100) =(1又2/3+2又3/4+3又4/5+...97又98/99+98又99/100)/【2×(1又2/3+2又3/4+3又4/5+...97又98/99+98又99/100)】=1/2...