3a-42=-3(a+4)

Solution for 3a-42=-3(a+4) equation:

Simplifying
3a + -42 = -3(a + 4)

Reorder the terms:
-42 + 3a = -3(a + 4)

Reorder the terms:
-42 + 3a = -3(4 + a)
-42 + 3a = (4 * -3 + a * -3)
-42 + 3a = (-12 + -3a)

Solving
-42 + 3a = -12 + -3a

Solving for variable 'a'.

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

Add '3a' to each side of the equation.
-42 + 3a + 3a = -12 + -3a + 3a

Combine like terms: 3a + 3a = 6a
-42 + 6a = -12 + -3a + 3a

Combine like terms: -3a + 3a = 0
-42 + 6a = -12 + 0
-42 + 6a = -12

Add '42' to each side of the equation.
-42 + 42 + 6a = -12 + 42

Combine like terms: -42 + 42 = 0
0 + 6a = -12 + 42
6a = -12 + 42

Combine like terms: -12 + 42 = 30
6a = 30

Divide each side by '6'.
a = 5

Simplifying
a = 5