2n+n+n+6=78

Solution for 2n+n+n+6=78 equation:

Simplifying
2n + n + n + 6 = 78

Reorder the terms:
6 + 2n + n + n = 78

Combine like terms: 2n + n = 3n
6 + 3n + n = 78

Combine like terms: 3n + n = 4n
6 + 4n = 78

Solving
6 + 4n = 78

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 + 4n = 78 + -6

Combine like terms: 6 + -6 = 0
0 + 4n = 78 + -6
4n = 78 + -6

Combine like terms: 78 + -6 = 72
4n = 72

Divide each side by '4'.
n = 18

Simplifying
n = 18