3.9-0.39=x

Solution for 3.9-0.39=x equation:

Simplifying
3.9 + -0.39 = x

Combine like terms: 3.9 + -0.39 = 3.51
3.51 = x

Solving
3.51 = 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.
3.51 + -1x = x + -1x

Combine like terms: x + -1x = 0
3.51 + -1x = 0

Add '-3.51' to each side of the equation.
3.51 + -3.51 + -1x = 0 + -3.51

Combine like terms: 3.51 + -3.51 = 0.00
0.00 + -1x = 0 + -3.51
-1x = 0 + -3.51

Combine like terms: 0 + -3.51 = -3.51
-1x = -3.51

Divide each side by '-1'.
x = 3.51

Simplifying
x = 3.51