Find the difference:

(i) $\dfrac{5}{6} - \dfrac{1}{4}$

(ii) $\dfrac{11}{8} - \dfrac{3}{4}$

(iii) $-\dfrac{7}{9} - \left(-\dfrac{2}{3}\right)$

(i) Given, $\dfrac{5}{6} - \dfrac{1}{4}$

L.C.M. of 6 and 4 = 12.

$\Rightarrow \dfrac{5}{6} - \dfrac{1}{4} \\[1em] \Rightarrow \dfrac{5 \times 2}{6 \times 2} - \dfrac{1 \times 3}{4 \times 3} \\[1em] \Rightarrow \dfrac{10}{12} - \dfrac{3}{12} \\[1em] \Rightarrow \dfrac{10 - 3}{12} \\[1em] \Rightarrow \dfrac{7}{12}.$

Hence, $\dfrac{5}{6} - \dfrac{1}{4} = \dfrac{7}{12}$.

(ii) Given, $\dfrac{11}{8} - \dfrac{3}{4}$

L.C.M. of 8 and 4 = 8.

$\Rightarrow \dfrac{11}{8} - \dfrac{3}{4} \\[1em] \Rightarrow \dfrac{11}{8} - \dfrac{3 \times 2}{4 \times 2} \\[1em] \Rightarrow \dfrac{11}{8} - \dfrac{6}{8} \\[1em] \Rightarrow \dfrac{11 - 6}{8} \\[1em] \Rightarrow \dfrac{5}{8}.$

Hence, $\dfrac{11}{8} - \dfrac{3}{4} = \dfrac{5}{8}$.

(iii) Given, $-\dfrac{7}{9} - \left(-\dfrac{2}{3}\right)$

L.C.M. of 9 and 3 = 9.

$\Rightarrow -\dfrac{7}{9} - \left(-\dfrac{2}{3}\right) \\[1em] \Rightarrow -\dfrac{7}{9} + \dfrac{2}{3} \\[1em] \Rightarrow -\dfrac{7}{9} + \dfrac{2 \times 3}{3 \times 3} \\[1em] \Rightarrow -\dfrac{7}{9} + \dfrac{6}{9} \\[1em] \Rightarrow \dfrac{-7 + 6}{9} \\[1em] \Rightarrow -\dfrac{1}{9}.$

Hence, $-\dfrac{7}{9} - \left(-\dfrac{2}{3}\right) = -\dfrac{1}{9}$.