42=2(9+n)

Solution for 42=2(9+n) equation:

Simplifying
42 = 2(9 + n)
42 = (9 * 2 + n * 2)
42 = (18 + 2n)

Solving
42 = 18 + 2n

Solving for variable 'n'.

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

Add '-2n' to each side of the equation.
42 + -2n = 18 + 2n + -2n

Combine like terms: 2n + -2n = 0
42 + -2n = 18 + 0
42 + -2n = 18

Add '-42' to each side of the equation.
42 + -42 + -2n = 18 + -42

Combine like terms: 42 + -42 = 0
0 + -2n = 18 + -42
-2n = 18 + -42

Combine like terms: 18 + -42 = -24
-2n = -24

Divide each side by '-2'.
n = 12

Simplifying
n = 12