$a$) `1 < |x - 3/4|`
`⇒` $\left\{\begin{matrix} x-\dfrac{3}{4} > 1\\x-\dfrac{3}{4} < -1 \end{matrix}\right.$
$⇒ \left\{\begin{matrix} x >\dfrac{7}{4}\\x < -\dfrac{1}{4} \end{matrix}\right. $
Vậy `x > 7/4; x < -1/4`.
$b$) `{11}/{17} - 0,625 < x- 1/3< 9/{13} + 2/3`
`⇔ 3/{136} < x-1/3< {53}/{39}`
`⇔ {145}/{408} < x < {22}/{13}`
Vậy ` {145}/{408} < x < {22}/{13}`.
$c$) `|4x-7| < 3`
`⇒` $\left\{\begin{matrix} 4x-7<3\\4x-7> -3 \end{matrix}\right.$
$⇒ \left\{\begin{matrix} x < \dfrac{5}{2}\\x>1 \end{matrix}\right. $
Vậy `1 < x < 5/2`.