n+[n+2]+[n+4]=42

Solution for n+[n+2]+[n+4]=42 equation:

Simplifying
n + [n + 2] + [n + 4] = 42

Reorder the terms:
n + [2 + n] + [n + 4] = 42

Remove brackets around [2 + n]
n + 2 + n + [n + 4] = 42

Reorder the terms:
n + 2 + n + [4 + n] = 42

Remove brackets around [4 + n]
n + 2 + n + 4 + n = 42

Reorder the terms:
2 + 4 + n + n + n = 42

Combine like terms: 2 + 4 = 6
6 + n + n + n = 42

Combine like terms: n + n = 2n
6 + 2n + n = 42

Combine like terms: 2n + n = 3n
6 + 3n = 42

Solving
6 + 3n = 42

Solving for variable 'n'.

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

Add '-6' to each side of the equation.
6 + -6 + 3n = 42 + -6

Combine like terms: 6 + -6 = 0
0 + 3n = 42 + -6
3n = 42 + -6

Combine like terms: 42 + -6 = 36
3n = 36

Divide each side by '3'.
n = 12

Simplifying
n = 12