`a)` `5(3-2x)+5(x-4)=6-4x`
`<=>` `5.3+5.(-2x)+5.x+5(-4)=6-4x`
`<=>` `15-10x+5x-20-6+4x=0`
`<=>` `-x-11=0`
`<=>` `-x=11`
`<=>` `x=-11`
Vậy `x=-11`
`b)` `-5(2-x)+4(x-3)=10x-15`
`<=>` `-5.2-5.(-x)+4.x+4.(-3)=10x-15`
`<=>` `-10+5x+4x-12=10x-15`
`<=>` `9x-22=10x-15`
`<=>` `9x-10x=-15+22`
`<=>` `-x=7`
`<=>` `x=-7`
Vậy `x=-7`
`color{Red}{I♥U}`