Question

РЕШИТЕ ПОЖАЛУЙСТА, С ОБЪЯСНЕНИЕМ!!!!!!!!
$3 \times ( - x) + 51 = 6 - 12$
$- 3x - 21 = 81 - 84$

Answer 1

3(-х)+51=6-12                 -3х-21=81-84
-3х+51=-6                        -3х=-3+21
-3х=-6-51                         -3х=18
-3х=-57                              х=18:(-3)
х=-57:(-3)                           х=-6
х=19