Đáp án:
`1: 0,25 . (1 1/4)^2 + 25 . [1 : (4/3)^2 : (5/4)^3] : [1 : (-2/3)^3]`
`= 1 : 1/4 . (5/4)^2 + 25 . [1 : 16/9 : 125/64] : [1 : (-8/27)]`
`= 1 . 4 . 25/16 + 25 . [1 . 9/16 . 64/125] : [ 1 . (-27/8)]`
`= 25/4 + 25 . 36/125 : (-27/8)`
`= 25/4 + 36/5 . (-8/27)`
`= 25/4 + -32/15`
`= 247/60`