464/441
454/441
1-8/9*2/7+5/7*3/7=1- 16/63 + 15/49=1- (7/63 +9/63) +15/49=1- 1/9 - 1/7 + 15/49=8/9 + 8/49=8*(1/9+1/49)=8* 58/441=464/441=1又23/441