123=-a+4(1-4a)

Solution for 123=-a+4(1-4a) equation:

Simplifying
123 = -1a + 4(1 + -4a)
123 = -1a + (1 * 4 + -4a * 4)
123 = -1a + (4 + -16a)

Reorder the terms:
123 = 4 + -1a + -16a

Combine like terms: -1a + -16a = -17a
123 = 4 + -17a

Solving
123 = 4 + -17a

Solving for variable 'a'.

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

Add '17a' to each side of the equation.
123 + 17a = 4 + -17a + 17a

Combine like terms: -17a + 17a = 0
123 + 17a = 4 + 0
123 + 17a = 4

Add '-123' to each side of the equation.
123 + -123 + 17a = 4 + -123

Combine like terms: 123 + -123 = 0
0 + 17a = 4 + -123
17a = 4 + -123

Combine like terms: 4 + -123 = -119
17a = -119

Divide each side by '17'.
a = -7

Simplifying
a = -7