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Đáp án+Giải thích các bước giải:

 `a,`

`-4/5+5/2x=-3/10`

`=> 5/2x=-3/10-(-4/5)`

`=> 5/2x=-3/10+4/5`

`=> 5/2x=-3/10+8/10`

`=> 5/2x=5/10`

`=> 5/2x=1/2`

`=> x=1/2:5/2`

`=> x=1/2x2/5`

`=> x=1/5

Vậy `x=1/5`

`b,`

`4/3+5/8:x=1/12`

`⇒5/8:x=1/12-4/3`

`=> 5/8:x=1/12-16/12`

`=> 5/8:x=-15/12`

`⇒5/8:x=-5/4`

`⇒x=5/8:-5/4`

`⇒x=-1/2`

`c,`

`(x-1/3)xx(x+2/5)=0`

`<=>` $\left[\begin{matrix} x-1/3=0\\ x+2/5=0\end{matrix}\right.$

`\text{TH1}: x-1/3=0`

`<=> x=0+1/3`

`<=> x=1/3`

`\text{TH2:} x+2/5=0`

`<=> x=0-2/5`

`<=> x=-2/5`

Vậy `x in {1/3;-2/5}`

`d,`

`(3/4x-9/16)xx(1,5+(-3)/5:x)=0`

`<=>` $\left[\begin{matrix} 3/4 x-9/16=0\\ 1,5+ -3/5:x=0\end{matrix}\right.$

`\text{TH1}: 3/4x-9/16=0`

`<=> 3/4x=0+9/16`

`<=> 3/4x=9/16`

`<=> x=9/16:3/4`

`<=> x=3/4`

`\text{TH2:} 1,5+ -3/5:x=0`

`<=>-3/5: x=1,5-0`

`<=> -3/5:x=1,5`

`<=> x=-3/5:1,5`

`<=> x=-3/5:3/2`

`<=> x=2/5`

Vậy `x in {3/4;2/5}`