Đáp án:
$a/$ `11 4/15 + (2 5/7 - 6 4/15)`
`= 11 4/15 + 2 5/7 - 6 4/15`
`= (11 4/15 - 6 4/15) + 2 5/7`
`= 5 + 19/7`
`= 54/7`
$b/$ `275% . (-0,4) - 2,75 . 1 3/5 + (-1,2) : 4/11`
`= (-11)/10 - 2,75 . 8/5 + (-33)/10`
`= (-11)/10 - 22/5 + (-33)/10`
`= (-11)/10 - 33/10 - 22/5`
`= (-22)/5 - 22/5`
`= (-44)/5`