Đáp án:
`↓↓↓`
Giải thích các bước giải:
`a)` `19/5 . 7/13 +19/5 . 9/13 - 19/5 . 3/13`
`=19/5 . (7/13 + 9/13 - 3/13 )`
`= 19/5 . ( 16/ 13 - 3/13 )`
`=19/5 . 1`
`= 19/5`
`b)` `\frac{-1}{6} . 3/5`
`= \frac{-1.3}{6.5}`
`=\frac{-1.3}{2.3 .5}`
`=\frac{-1.1}{2.1 .5}`
`=\frac{-1}{10}`
`c)` `-1,4 . 15/-49 - ( 40 % + 4/3 ) : 2 3/5 `
`=-7/5 . 15/-49- ( 2/5 + 4/3 ) : 13/5`
`= \frac{-7.15}{5.(-49)}-26/15 : 13/5`
`=\frac{-7.3.5}{5.(-7).7}-26/15: 5/13`
`=\frac{-1.3.1}{5.(-1).7}- \frac{-26.5}{15.13}`
`=3/35-\frac{-26.5}{3.5.13}`
`=3/35-\frac{-26.1}{3.1.13}`
`=3/35-\frac{-26}{39}`
`=19/15`
