Đáp án:
$\\$
`a,`
`(-2) . 1 2/3 - 2/3 : (-2)`
`=(-2) . 5/3 - 2/3 . (-1)/2`
`= (-10)/3 + 1/3`
`= -3`
`b,`
`( (-1)/999 - 2004/2005) : 7/3 + ( 1000/999 - 1/2005) . 3/7`
`= ( (-1)/999 - 2004/2005) . 3/7 + (1000/999 - 1/2005) . 3/7`
`= [ (-1)/999 - 2004/2005 + 1000/999 - 1/2005] . 3/7`
`= [ ( (-1)/99 + 1000/999) + ( (-2004)/2005 - 1/2005)].3/7`
`= [1 + (-1)].3/7`
`= 0.3/7`
`= 0`