`a)` `\frac{x}{16}=-\frac{11}{12}`

`=>x. 12=-11. 16`

`=>x. 12=-176`

`=>x=-176/12=-44/3`

Vậy `x=-44/3`

`b)` `\frac{12}{x}=\frac{3}{-8}`

`=>12. (-8)=x. 3`

`=>-96=x. 3`

`=>x=-32`

Vậy `x=-32`

`c)` `\frac{4}{5}=\frac{-12}{9-x}`

`=>4. (9-x)=5. (-12)`

`=>36-4. x=-60`

`=>4. x=96`

`=>x=24`

Vậy `x=24`

`d)` `\frac{x}{-5}=\frac{-5}{x}`

`x. x=(-5). (-5)`

`=>x^2=25`

`=>x=+-5`

Vậy `x=+-5`

`e)` `\frac{1}{2}=\frac{3x+1}{3x}`

`=>(3x+1). 2=3x. 1`

`=>6x+2=3x`

`=>3x=−2`

`=>x=-2/3`

Vậy `x=-2/3`