`a)`
Ta có :
`-1/5 < 0`
`1/1000 > 0`
`=> -1/5 < 1/1000`
`b)`
Ta có :
`13/38 > 13/39 = 1/3`
`29/88 < 29/87 = 1/3`
`=> 13/38 > 29/88`
`=> -13/38 < 29/(-88)`
`c)`
Ta có :
`267/268 < 1`
`1347/1343 > 1`
`=> 267/268 < 1347/1343`
`=> 267/(-268) > (-1347)/1343`
`d)`
Ta có :
`(-181818)/(313131) = (-181818 : 10101)/(313131 : 10101) = (-18)/31`
`=> (-181818)/(313131) = (-18)/31`