`a, (2x-1/2) .2+(1/2+1/3+1/4):1/8=1`
`⇒ (2x-1/2) .2+13/12:1/8=1`
`⇒ (2x-1/2) .2+26/3=1`
`⇒ (2x-1/2) .2 = -23/3`
`⇒ 2x - 1/2 = -23/6`
`⇒ 2x = -10/3`
`⇒ x = -5/3`
`b, (x - 3)(4 - 5x) = 0`
`⇒` \(\left[ \begin{array}{l}x - 3=0\\4 - 5x=0\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x = 3\\ 5x=4\end{array} \right.\)
`⇒ x = 5` và `x = 4/5`