Hasil dari 12/4 = x/10-x adalah?

3 = x / 10 – x
30 – 3x = x
30 = 4x
7,5 = x

12/4 = x/10 – x
3 = x/10 – x
3 = -9x/10
-9x = 30
x = -10/3
  = -3,333333…