`[x-5]/195+[x-7]/193=[x-2]/198+[x-3]/197`
`<=>[x-5]/195-1+[x-7]/193-1=[x-2]/198-1+[x-3]/197-1`
`<=>[x-5-195]/195+[x-7-193]/193=[x-2-198]/198+[x-3-197]/197`
`<=>[x-200]/195+[x-200]/193-[x-200]/198-[x-200]/197=0`
`<=>(x-200)(1/195+1/193-1/198-1/197)=0`
Mà `1/195+1/193-1/198-1/197 \ne 0`
`=>x-200=0`
`<=>x=200`
Vậy `S={200}`