Đáp án:+Giải thích các bước giải:
`e) 28/45 - ( 8/45 - 17/51 - 3/11) `
`=28/45-8/45+17/51+3/11`
`=4/9+17/51+3/11`
`=4/9+1/3+3/11`
`=44/99+33/99+27/11`
`=(44+33+27)/11`
`=104/11`
`f) ( 11/4 - 5/9 - 4/9 × 11/4 ) × 8/13`
`=(11/4-5/9-11/9)*8/13`
`=[11/4-(5/9+11/9)]*8/13`
`=(11/4-16/9)*8/13`
`=(99/36-64/36)*8/13`
`=35/36*8/13`
`=(35*8)/(36*13)`
`=(35*4*2)/(4*9*13)`
`=(35*2)/(9*13)`
`=70/117`