`a,(5/14-12/11+7/5)-(3-1/2-45/11)+(23/14-2/5)`
`=5/14-12/11+7/5-3+1/2+45/11+23/14-2/5`
`=(5/14+23/14)+(-12/11+45/11)+(7/5-2/5)-3+1/2`
`=2+3+1-3+1/2`
`=3+1/2`
`=7/2`
`a,46 2/3.(-4/5)-56 2/3.(-4/5)`
`=140/3 . (-4/5) - 170/3 . (-4/5)`
`= (-4/5) . (140/3 - 170/3)`
`= (-4/5) . (-10)`
`= 8`
`b, \frac{3,5-2x}{4}=-7/8`
`⇔ \frac{2(3,5 - 2x)}{8}=-7/8`
`⇒2(3,5-2x)=-7`
`⇔7-4x=-7`
`⇔-4x=-14`
`⇔x=7/2`
$\text{Vậy x = $\dfrac{7}{2}$}$