400=1-(1+x)

Solution for 400=1-(1+x) equation:

Simplifying
400 = 1 + -1(1 + x)
400 = 1 + (1 * -1 + x * -1)
400 = 1 + (-1 + -1x)

Combine like terms: 1 + -1 = 0
400 = 0 + -1x
400 = -1x

Solving
400 = -1x

Solving for variable 'x'.

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

Add 'x' to each side of the equation.
400 + x = -1x + x

Combine like terms: -1x + x = 0
400 + x = 0

Add '-400' to each side of the equation.
400 + -400 + x = 0 + -400

Combine like terms: 400 + -400 = 0
0 + x = 0 + -400
x = 0 + -400

Combine like terms: 0 + -400 = -400
x = -400

Simplifying
x = -400