Find $(m + n) ÷ (m - n)$, if;

$m = \dfrac{4}{5}$ and $n = -\dfrac{3}{10}$

$(m + n) ÷ (m - n)\\[1em] =\Big[\dfrac{4}{5} + \Big(-\dfrac{3}{10}\Big)\Big] ÷ \Big[\dfrac{4}{5} - \Big(-\dfrac{3}{10}\Big)\Big]$

LCM of 5 and 10 is 2 x 5 = 10

$= \Big[\dfrac{4 \times 2}{5 \times 2} + \Big(-\dfrac{3 \times 1}{10 \times 1}\Big)\Big] ÷ \Big[\dfrac{4 \times 2}{5 \times 2} - \Big(-\dfrac{3 \times 1}{10 \times 1}\Big)\Big]\\[1em] = \Big[\dfrac{8}{10} + \Big(-\dfrac{3}{10}\Big)\Big] ÷ \Big[\dfrac{8}{10} - \Big(-\dfrac{3}{10}\Big)]\\[1em] = \Big[\dfrac{8 + (-3)}{10}\Big] ÷ \Big[\dfrac{8 - (-3)}{10}\Big]\\[1em] = \Big[\dfrac{5}{10}\Big] ÷ \Big[\dfrac{11}{10}\Big]\\[1em] = \dfrac{5}{10} \times \dfrac{10}{11}\\[1em] = \dfrac{5 \times 10}{10 \times 11}\\[1em] = \dfrac{50}{110}\\[1em] = \dfrac{5}{11}$

If $m$ = $\dfrac{4}{5}$ and $n$ = -$\dfrac{3}{10}$ then $(m + n) ÷ (m - n) = \dfrac{5}{11}$.