Đáp án:
`a, 3/5`
`b, (-4)/9`
`c, 0`
Giải thích các bước giải:
`a,`
`2/3 + 1/5 - 4/15`
`= 10/15 + 3/15 - 4/15`
`= (10 + 3 - 4)/15`
`= 9/15`
`= 3/5`
`b,`
`(-4)/11 × 8/9 + (-4)/11 × 3/9`
`= (-4)/11 × (8/9 + 3/9)`
`= (-4)/11 × 11/9`
`= (-4)/9`
`c,`
`25% × 2/3 - 1 1/2 × 1/6 + 1/12`
`= 1/4 × 2/3 - 3/2 × 1/6 + 1/12`
`= 1/6 - 3/2 × 1/6 + 1/12`
`= 1/6 × (1 - 3/2) + 1/12`
`= 1/6 × (2/2-3/2) + 1/12`
`= 1/6 × (-1)/2 + 1/12`
`= (-1)/12 + 1/12`
`= 0`
