a, `A = 25.30+10`
`=> A = (26-1).(31-1)+10`
`=>A = 26.31-31-26+1+10`
`=> A = 26.31-46`
Mà B = 26.31 - 10
`=>` A < B
b, `C=137.454+206 `
`=> C = (138-1)(454-1)+206`
`=> C = 138.454 - 454 - 138 + 1 +206`
`=> C = 138.454-385`
Mà `D = 138.454-10`
`=> C < D`