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`1.`

`3/4 x +5=-10`

`->3/4 x=-10-5`

`-> 3/4 x=-15`

`->x=-15 : 3/4`

`->x=-20`

Vậy `x=-20`

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`2.`

`1/4 + 3/4 : x=-2`

`-> 3/4 :x=-2 - 1/4`

`-> 3/4 :x=(-8)/4-1/4`

`->3/4 :x=(-9)/4`

`->x=3/4 : (-9)/4`

`->x=3/4 . (-4)/9`

`->x=(-1)/3`

Vậy `x=(-1)/3`

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`3.`

`(x-5)/(3x +2)=(-2)/5 (x \ne (-2)/3)`

`-> (x-5) . 5 = (3x+2) . (-2)`

`-> 5x-25=-6x - 4`

`-> 5x+6x=25-4`

`-> 11x=21`

`-> x=21 : 11`

`->x=21/11` (Thỏa mãn)

Vậy `x=21/11`

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`4.`

`(x+1)/13 + (x+2)/12=(x+3)/11 + (x+4)/10`

`-> (x+1)/13 + (x+2)/12 +2=(x+3)/11 + (x+4)/10 +2`

`-> ( (x+1)/13+1) + ( (x+2)/12+1) = ( (x+3)/11+1) + ( (x+4)/10+1)`

`-> ( (x+1)/13 +13/13) + ( (x+2)/12 +12/12) = ( (x+3)/11+ 11/11) + ( (x+4)/10 +10/10)`

`-> (x+14)/13 + (x+14)/12 = (x+14)/11 + (x+14)/10`

`-> (x+14)/13 + (x+14)/12-  (x+14)/11 - (x+14)/10=0`

`-> (x+14) (1/13 +1/12 - 1/11-1/10)=0`

`->x+14=0` (Do `1/13 +1/12 - 1/11-1/10 \ne 0`)

`->x=0-14`

`->x=-14`

Vậy `x=-14`

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`5.`

`(x+207)/100 + (x+205)/99 = (x+203)/98 + (x+201)/97`

`-> (x+207)/100 + (x+205)/99 - 4 = (x+203)/98 + (x+201)/97 - 4`

`-> ( (x+207)/100 - 2) + ( (x+205)/99-2) = ( (x+203)/98-2) + ( (x+201)/97-2)`

`-> ( (x+207)/100 - 200/100) + ( (x+205)/99 - 198/99) = ( (x+203)/98 - 196/98) + ( (x+201)/97 - 194/97)`

`-> (x + 7)/100 + (x+7)/99 = (x+7)/98 + (x+7)/97`

`-> (x + 7)/100 + (x+7)/99 - (x+7)/98 - (x+7)/97 =0`

`-> (x+7) (1/100 +1/99 - 1/98 - 1/97)=0`

`->x+7=0` (Do `1/100 +1/99 - 1/98 - 1/97 \ne 0`)

`->x=0-7`

`->x=-7`

Vậy `x=-7`