ta có:6/13=12/26 và 7/13 =14/26
12/26 < 13/26 < 14/26 => phân số đó = 13/26
13/26 vì 6/13=12/26
7/13=14/26
=>12/26<13/26<14/26
ta co 6/13=12/26 ; 7/13=14/26 =>12/26<X<14/26 =>x=13/26 vay phan so lon hon 6/13 va nho hon 7/13 ma co mau so bang 26 la phan so 13/26 o tren dau bai lam ban ghi cho minh la:goi phan so can tim la x