Giải thích các bước giải:
`a) 6 1/5 .(-2)/7 + 14 4/5 .(-2/7)`
` = (-2)/7 .(6 1/5 + 14 4/5)`
` = (-2)/7 .[ (6+14) + (1/5 + 4/5)]`
` = (-2)/7 . (20 +1) = (-2)/7 . 21`
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`b) 7 1/6 .(-7)/6 + 10 5/6 .(-7)/6`
` = (-7)/6 .( 7 1/6 + 10 5/6)`
` = (-7)/6 . [(7+10) + (1/6+5/6)]`
` = (-7)/6 . (17 + 1)= (-7)/6 . 18`
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`c) 5/7 . 5/11 + 5/7 . 2/11- 5/7. 14/11`
` = 5/7. (5/11 + 2/11 - 14/11) = 5/7 . (-7)/11`
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`f) 19 5/8: 7/12- 15 1/4:7/12`
` = 19 5/8 . 12/7 - 15 1/4 . 12/7`
` = ( 19 5/8 - 15 1/4).12/7 `
` = [(19-15) + (5/8-1/4)].12/7`
` = (4 + 3/8).12/7= 4 3/(8) . 12/7`
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`g) 2/5. 1/3- 2/15 : 1/5+ 3/5. 1/3`
` = 2/5 . 1/3 - 2/15 . 5 + 3/5 . 1/3`
` = 2/5 . 1/3 - 2/3 + 3/5 . 1/3`
` =2/5 . 1/3 - 2.1/3 + 3/5 . 1/3`
` = 1/3.(2/5 - 2 +3/5) =1/3. (-1)`
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`h) 4/9. 19 1/3- 4/9. 39 1/3`
` = 4/9.(19 1/3 - 39 1/3)`
` = 4/9 . [(19 -39) + (1/3-1/3)] = 4/9 . (-20)`
