Question

3x - 1 + 3x + 3x +1 = 13/ 27

Answer 1

  9x = 13/27 = ~ 0,5, ou seja, 0,5 - 1 = -1/2 espero que entenda

Answer 2

$3x-1+3x+3x+1= \frac{13}{27} \\\\ 3x + 3x +3x + 1 -1 = \frac{13}{27}$
$9x = \frac{13}{27} \\\\ x = \frac{1}{9}.\frac{13}{27}$
$x = \frac{1}{9}.\frac{13}{27} \\\\ x = \frac{13}{243}$