a+(a+6)=42

Solution for a+(a+6)=42 equation:

Simplifying
a + (a + 6) = 42

Reorder the terms:
a + (6 + a) = 42

Remove parenthesis around (6 + a)
a + 6 + a = 42

Reorder the terms:
6 + a + a = 42

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

Solving
6 + 2a = 42

Solving for variable 'a'.

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

Add '-6' to each side of the equation.
6 + -6 + 2a = 42 + -6

Combine like terms: 6 + -6 = 0
0 + 2a = 42 + -6
2a = 42 + -6

Combine like terms: 42 + -6 = 36
2a = 36

Divide each side by '2'.
a = 18

Simplifying
a = 18