Đáp án:
Bài 1
$a,$ `-1/4 + 3/4 + (-5/4)`
`= 2/4 + (-5/4)`
`= -3/4`
$b,$ `1,4 . 15/49 - (4/5 + 2/3) : 11/5`
`= 3/7 - 22/15 : 11/5`
`= 3/7 - 2/3`
`= (-5)/21`
Bài 2
$a,$ `-7/15 + 3/11 - 2/7 - (-7/15) + (-14/11)`
`= -7/15 + 3/11 - 2/3 + 7/15 - 14/11`
`= (-7/15 + 7/15) + (3/11 - 14/11) - 2/3`
`= 0 - 1 - 2/3`
`= -1 - 2/3`
`= -5/3`
$b,$ `113 . (-11) + 113 . (-115) - 13 . (-126)`
`= 113 . [-11 + (-115)] - 13 . (-126)`
`= 113 . (-126) - 13 . (-126)`
`= -126 . (113 - 13)`
`= -126 . 100`
`= -12600`