.3(5n+12)+.3n=-1

Solution for .3(5n+12)+.3n=-1 equation:

Simplifying
0.3(5n + 12) + 0.3n = -1

Reorder the terms:
0.3(12 + 5n) + 0.3n = -1
(12 * 0.3 + 5n * 0.3) + 0.3n = -1
(3.6 + 1.5n) + 0.3n = -1

Combine like terms: 1.5n + 0.3n = 1.8n
3.6 + 1.8n = -1

Solving
3.6 + 1.8n = -1

Solving for variable 'n'.

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

Add '-3.6' to each side of the equation.
3.6 + -3.6 + 1.8n = -1 + -3.6

Combine like terms: 3.6 + -3.6 = 0.0
0.0 + 1.8n = -1 + -3.6
1.8n = -1 + -3.6

Combine like terms: -1 + -3.6 = -4.6
1.8n = -4.6

Divide each side by '1.8'.
n = -2.555555556

Simplifying
n = -2.555555556