Đáp án:
$a/$ `(3/8 + (-3)/4 + 7/12) : 5/6 + 1/2`
`= (-3/8 + 7/12) : 5/6 + 1/2`
`= 5/24 : 5/6 + 1/2`
`= 1/4 + 1/2`
`= 3/4`
$b/$ `(-3)/7 . 5/9 + 4/9 . (-3)/7 + 2 3/7`
`= (-3)/7 . (5/9 + 4/9) + 17/7`
`= (-3)/7 . 1 + 17/7`
`= (-3)/7 + 17/7`
`= 14/7`
`= 2`