.40x+.05(12-x)=.10(-15)

Solution for .40x+.05(12-x)=.10(-15) equation:

Simplifying
0.40x + 0.05(12 + -1x) = 0.10(-15)
0.40x + (12 * 0.05 + -1x * 0.05) = 0.10(-15)
0.40x + (0.6 + -0.05x) = 0.10(-15)

Reorder the terms:
0.6 + 0.40x + -0.05x = 0.10(-15)

Combine like terms: 0.40x + -0.05x = 0.35x
0.6 + 0.35x = 0.10(-15)

Multiply 0.10 * -15
0.6 + 0.35x = -1.5

Solving
0.6 + 0.35x = -1.5

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 + 0.35x = -1.5 + -0.6

Combine like terms: 0.6 + -0.6 = 0.0
0.0 + 0.35x = -1.5 + -0.6
0.35x = -1.5 + -0.6

Combine like terms: -1.5 + -0.6 = -2.1
0.35x = -2.1

Divide each side by '0.35'.
x = -6

Simplifying
x = -6