a) `x - 1/6 . -1/2 = -1/5 : 4`
`⇒ x + 1/12 = -1/20`
`⇒ x = -2/15`
b) `2x + -1/6 : (-3) = -4/5 - -6/7`
`⇒ 2x + 1/2 = 2/35`
`⇒ 2x = 31/70`
`⇒ x = 31/140`
c) `5x - -1/5 : -2/25 = 24 - 1/7`
`⇒ 5x - 5/2 = 167/7`
`⇒ 5x = 369/14`
`⇒ x = 369/70`
d) `(x - 1/8)^2 = -1/5 . -1/20`
`⇒ (x - 1/8)^2 = 1/100 = ±(1/10)^2`
$\ \left[ \begin{array}{l}x-\dfrac{1}{8} = \dfrac{1}{10}\\x-\dfrac{1}{8} = \dfrac{-1}{10}\end{array} \right.$
$\ \left[ \begin{array}{l}x=\dfrac{9}{40}\\x=\dfrac{1}{40}\end{array} \right.$
