$\text{Đáp án+giải thích các bước giải:}$
$\dfrac{13}{20}$ × -7$\dfrac{1}{2}$ - $\dfrac{13}{20}$ × 12$\dfrac{1}{5}$
$\text{=}$ $\dfrac{13}{20}$ ×( $\dfrac{-15}{2}$ )- $\dfrac{13}{20}$ × $\dfrac{61}{5}$
$\text{=}$ $\dfrac{13}{20}$ × ($\dfrac{-15}{2}$ -$\dfrac{61}{5}$ )
$\text{=}$ $\dfrac{13}{20}$ × ($\dfrac{-197}{10}$)
$\text{=}$ $\dfrac{-2561}{200}$
$\dfrac{x-1}{x+5}$ = $\dfrac{6}{7}$
$\text{⇒(x - 1) . 7 = (x + 5) . 6}$
$\text{⇒ 7x - 7 = 6x + 30}$
$\text{⇒ 7x - 6x = 30 + 7}$
$\text{⇒ x = 37}$
