-123=3(1+7x)

Solution for -123=3(1+7x) equation:

Simplifying
-123 = 3(1 + 7x)
-123 = (1 * 3 + 7x * 3)
-123 = (3 + 21x)

Solving
-123 = 3 + 21x

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '-21x' to each side of the equation.
-123 + -21x = 3 + 21x + -21x

Combine like terms: 21x + -21x = 0
-123 + -21x = 3 + 0
-123 + -21x = 3

Add '123' to each side of the equation.
-123 + 123 + -21x = 3 + 123

Combine like terms: -123 + 123 = 0
0 + -21x = 3 + 123
-21x = 3 + 123

Combine like terms: 3 + 123 = 126
-21x = 126

Divide each side by '-21'.
x = -6

Simplifying
x = -6