42-2(9+3)=a

Solution for 42-2(9+3)=a equation:

Simplifying
42 + -2(9 + 3) = a

Combine like terms: 9 + 3 = 12
42 + -2(12) = a

Multiply -2 * 12
42 + -24 = a

Combine like terms: 42 + -24 = 18
18 = a

Solving
18 = a

Solving for variable 'a'.

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

Add '-1a' to each side of the equation.
18 + -1a = a + -1a

Combine like terms: a + -1a = 0
18 + -1a = 0

Add '-18' to each side of the equation.
18 + -18 + -1a = 0 + -18

Combine like terms: 18 + -18 = 0
0 + -1a = 0 + -18
-1a = 0 + -18

Combine like terms: 0 + -18 = -18
-1a = -18

Divide each side by '-1'.
a = 18

Simplifying
a = 18