n+(3+n)+(2n)+(7+n)+2(3+n)=121

Solution for n+(3+n)+(2n)+(7+n)+2(3+n)=121 equation:

Simplifying
n + (3 + n) + (2n) + (7 + n) + 2(3 + n) = 121

Remove parenthesis around (3 + n)
n + 3 + n + (2n) + (7 + n) + 2(3 + n) = 121

Remove parenthesis around (7 + n)
n + 3 + n + (2n) + 7 + n + 2(3 + n) = 121
n + 3 + n + (2n) + 7 + n + (3 * 2 + n * 2) = 121
n + 3 + n + (2n) + 7 + n + (6 + 2n) = 121

Reorder the terms:
3 + 7 + 6 + n + n + (2n) + n + 2n = 121

Combine like terms: 3 + 7 = 10
10 + 6 + n + n + (2n) + n + 2n = 121

Combine like terms: 10 + 6 = 16
16 + n + n + (2n) + n + 2n = 121

Combine like terms: n + n = 2n
16 + 2n + (2n) + n + 2n = 121

Combine like terms: 2n + (2n) = 4n
16 + 4n + n + 2n = 121

Combine like terms: 4n + n = 5n
16 + 5n + 2n = 121

Combine like terms: 5n + 2n = 7n
16 + 7n = 121

Solving
16 + 7n = 121

Solving for variable 'n'.

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

Add '-16' to each side of the equation.
16 + -16 + 7n = 121 + -16

Combine like terms: 16 + -16 = 0
0 + 7n = 121 + -16
7n = 121 + -16

Combine like terms: 121 + -16 = 105
7n = 105

Divide each side by '7'.
n = 15

Simplifying
n = 15