.15x+.05(12-x)=.10(4)

Solution for .15x+.05(12-x)=.10(4) equation:

Simplifying
0.15x + 0.05(12 + -1x) = 0.10(4)
0.15x + (12 * 0.05 + -1x * 0.05) = 0.10(4)
0.15x + (0.6 + -0.05x) = 0.10(4)

Reorder the terms:
0.6 + 0.15x + -0.05x = 0.10(4)

Combine like terms: 0.15x + -0.05x = 0.1x
0.6 + 0.1x = 0.10(4)

Multiply 0.10 * 4
0.6 + 0.1x = 0.4

Solving
0.6 + 0.1x = 0.4

Solving for variable 'x'.

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

Add '-0.6' to each side of the equation.
0.6 + -0.6 + 0.1x = 0.4 + -0.6

Combine like terms: 0.6 + -0.6 = 0.0
0.0 + 0.1x = 0.4 + -0.6
0.1x = 0.4 + -0.6

Combine like terms: 0.4 + -0.6 = -0.2
0.1x = -0.2

Divide each side by '0.1'.
x = -2

Simplifying
x = -2