Tong 3 so bang 120,khi chuyen tu so thu nhat sang so thu hai 8 don vi va chuyen sang so thu ba 10 don vi va chuyen tu so thu hai sang so thu nhat 15 don vi thi so thu hai gap ruoi so thu nhat va bang 3/7 so thu ba. GIAI RA GIUP MK DE MK BIET CACH LAM NHE SORRY VI DA KO CO DAU