原式=(2/3+2/15)+(2/8+2/24+2/48)+(2/35+2/63)+2/80 =4/5+3/8+4/45+1/40 =(36/45+4/45)+(15/40+1/40) =8/9+2/5 =58/45
=(2/3+2/15)+(2/8+2/24+2/48)+(2/35+2/63)+2/80 =4/5+3/8+4/45+1/40 =(36/45+4/45)+(15/40+1/40) =8/9+2/5 =58/45