Đáp án:
$b/$ `(-5)/7 . 2/11 + (-5)/7 . 9/11 + 1 5/7`
`= (-5)/7 . (2/11 + 9/11) + 12/7`
`= (-5)/7 . 1 + 12/7`
`= (-5)/7 + 12/7`
`= 1`
$c/$ `11 3/13 - (2 4/7 + 5 3/13)`
`= 11 3/13 - 2 4/7 - 5 3/13`
`= (11 3/13 - 5 3/13) - 18/7`
`= 6 - 18/7`
`= 24/7`
$d/$ `2/7 . 5 1/4 - 2/7 . 3 1/4`
`= 2/7 . (5 1/4 - 3 1/4)`
`= 2/7 . 2`
`= 4/7`