6=-2[7-c]

Solution for 6=-2[7-c] equation:

Simplifying
6 = -2[7 + -1c]
6 = [7 * -2 + -1c * -2]
6 = [-14 + 2c]

Solving
6 = -14 + 2c

Solving for variable 'c'.

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

Add '-2c' to each side of the equation.
6 + -2c = -14 + 2c + -2c

Combine like terms: 2c + -2c = 0
6 + -2c = -14 + 0
6 + -2c = -14

Add '-6' to each side of the equation.
6 + -6 + -2c = -14 + -6

Combine like terms: 6 + -6 = 0
0 + -2c = -14 + -6
-2c = -14 + -6

Combine like terms: -14 + -6 = -20
-2c = -20

Divide each side by '-2'.
c = 10

Simplifying
c = 10