n+(n+1)+(n+2)+(n+3)=90

Solution for n+(n+1)+(n+2)+(n+3)=90 equation:

Simplifying
n + (n + 1) + (n + 2) + (n + 3) = 90

Reorder the terms:
n + (1 + n) + (n + 2) + (n + 3) = 90

Remove parenthesis around (1 + n)
n + 1 + n + (n + 2) + (n + 3) = 90

Reorder the terms:
n + 1 + n + (2 + n) + (n + 3) = 90

Remove parenthesis around (2 + n)
n + 1 + n + 2 + n + (n + 3) = 90

Reorder the terms:
n + 1 + n + 2 + n + (3 + n) = 90

Remove parenthesis around (3 + n)
n + 1 + n + 2 + n + 3 + n = 90

Reorder the terms:
1 + 2 + 3 + n + n + n + n = 90

Combine like terms: 1 + 2 = 3
3 + 3 + n + n + n + n = 90

Combine like terms: 3 + 3 = 6
6 + n + n + n + n = 90

Combine like terms: n + n = 2n
6 + 2n + n + n = 90

Combine like terms: 2n + n = 3n
6 + 3n + n = 90

Combine like terms: 3n + n = 4n
6 + 4n = 90

Solving
6 + 4n = 90

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 = 90 + -6

Combine like terms: 6 + -6 = 0
0 + 4n = 90 + -6
4n = 90 + -6

Combine like terms: 90 + -6 = 84
4n = 84

Divide each side by '4'.
n = 21

Simplifying
n = 21