`c)`

`(x-1)/99 + (x-3)/97 + (x-5)/95 < (x-2)/98 + (x-4)/96 + (x-6)/94`

`<=> ((x-1)/99 - 1) + ((x-3)/97 - 1) + ((x-5)/95 -1) < ((x-2)/98 - 1) + ((x-4)/96 -1) + ((x-6)/94 -1)`

`<=> (x-100)/99 + (x-100)/97 + (x-100)/95 - (x-100)/98 - (x-100)/96 - (x-100)/94 <0`

`<=> (x-100) (1/99 + 1/97 + 1/95 - 1/98 - 1/96 - 1/94)<0`

Vì `1/99 + 1/97 + 1/95 - 1/98 - 1/96 - 1/94 <0`

`=>x-100>0`

`<=>x>100`

Vậy `S={x|x>100}`.

`d)`

`(x-1009)/1001 + (x-4)/1003 + (x+2010)/1005 <= 7`

`<=> ((x-1009)/1001 - 1) + ((x-4)/1003 -2) + ((x+2010)/1005 -4) <= 0`

`<=> (x-2010)/1001 + (x-2010)/1003 + (x-2010)/1005 <= 0`

`<=> (x-2010)(1/1001 + 1/1003 + 1/1005) <= 0`

Vì `1/1001 + 1/1003 + 1/1005 > 0`

`=> x-2010 <= 0`

`<=> x<= 2010`

Vậy `S={x|x<= 2010}`.