.40*9=x

Solution for .40*9=x equation:

Simplifying
0.40 * 9 = x

Multiply 0.40 * 9
3.6 = x

Solving
3.6 = x

Solving for variable 'x'.

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

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

Combine like terms: x + -1x = 0
3.6 + -1x = 0

Add '-3.6' to each side of the equation.
3.6 + -3.6 + -1x = 0 + -3.6

Combine like terms: 3.6 + -3.6 = 0.0
0.0 + -1x = 0 + -3.6
-1x = 0 + -3.6

Combine like terms: 0 + -3.6 = -3.6
-1x = -3.6

Divide each side by '-1'.
x = 3.6

Simplifying
x = 3.6