a) 8 / 9 = 2 / 9 + 6 / 9 sau 8 / 9 = 5 / 9 + 3 / 9 , 8 / 9 = 7 / 9 + 1 / 9
b) 6 / 7 = 4 / 7 + 2 / 7; 6 / 7 = 3 / 7 + 3 / 7; 6 / 7 = 1 / 7 + 5 / 7
c) 5 / 8 = 1 / 8 + 4 / 8 ; 5 / 8 = 2 / 8 + 3 / 8 ; 5 / 8 = 3 / 8 + 2 / 8
d) 7 / 10 = 3 / 10 + 4 / 10 ; 7 / 10 = 2 / 10 + 5 / 10; 6 / 10 + 1 / 10 = 7 / 10