\(12+3.\left(-x+7\right)=-18\)
\(12-3x+21=-18\)
\(33-3x=-18\)
\(-3x=-18-33\)
\(-3x=-51\)
\(x=\left(-51\right):\left(-3\right)\)
\(x=17\)
Vậy \(x=17\)
12 + 3 . (-x + 7) = -18
=> 3 . (-x + 7) = -18 - 12
=> 3 . (-x + 7) = -30
=> -x + 7 = -30 : 3
=> -x + 7 = -10
=> -x = -10 - 7
=> -x = -17
=> x = 17
12 + 3.(-x + 7) = -18
3.(-x + 7) = (-18) - 12
3.(-x + 7) = -30
-x + 7 = (-30) : 3
-x + 7 = -10
-x = (-10) - 7
-x = -17
x = 17
12 + 3.(-x + 7) = -18
3.(-x + 7) = (-18) - 12
3.(-x + 7) = -30
-x + 7 = (-30) : 3
-x + 7 = -10
-x = (-10) - 7
-x = -17
x = 17
12 + 3.(-x + 7) = -18
3.(-x + 7) = (-18) - 12
3.(-x + 7) = -30
-x + 7 = (-30) : 3
-x + 7 = -10
-x = (-10) - 7
-x = -17
x = 17
12 + 3 . (-x + 7) = -18
=> 3 . (-x + 7) = -18 - 12
=> 3 . (-x + 7) = -30
=> -x + 7 = -30 : 3
=> -x + 7 = -10
=> -x = -10 - 7
=> -x = -17
=> x = 17