30+12=a-42

Solution for 30+12=a-42 equation:

Simplifying
30 + 12 = a + -42

Combine like terms: 30 + 12 = 42
42 = a + -42

Reorder the terms:
42 = -42 + a

Solving
42 = -42 + 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.
42 + -1a = -42 + a + -1a

Combine like terms: a + -1a = 0
42 + -1a = -42 + 0
42 + -1a = -42

Add '-42' to each side of the equation.
42 + -42 + -1a = -42 + -42

Combine like terms: 42 + -42 = 0
0 + -1a = -42 + -42
-1a = -42 + -42

Combine like terms: -42 + -42 = -84
-1a = -84

Divide each side by '-1'.
a = 84

Simplifying
a = 84