$\text{a, }$ `-7/5` `+` `2/5`
`= \frac{-7 + 2}{5}`
`= -5/5`
`= 1`
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$\text{b, }$ `5/7 + ( -10/14)`
`= 10/14 - 10/14`
`= 0`
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$\text{c, }$ `-7/10 . 5/14`
`= \frac{-7 . 5}{10 . 14}`
`= \frac{-1 . 1}{2 . 2}`
`= -1/4`
-----------------------------------------
$\text{d, }$ `-3/7 . 9/11 + -3/7 . 2/11`
`= -3/7( 9/11 + 2/11)`
`= -3/7 . 1`
`= -3/7`