3.9=x

Solution for 3.9=x equation:

Simplifying
3.9 = x

Solving
3.9 = 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.
3.9 + -1x = x + -1x

Combine like terms: x + -1x = 0
3.9 + -1x = 0

Add '-3.9' to each side of the equation.
3.9 + -3.9 + -1x = 0 + -3.9

Combine like terms: 3.9 + -3.9 = 0.0
0.0 + -1x = 0 + -3.9
-1x = 0 + -3.9

Combine like terms: 0 + -3.9 = -3.9
-1x = -3.9

Divide each side by '-1'.
x = 3.9

Simplifying
x = 3.9