3.9x-2.1x+4.6=15.5

Solution for 3.9x-2.1x+4.6=15.5 equation:

Simplifying
3.9x + -2.1x + 4.6 = 15.5

Reorder the terms:
4.6 + 3.9x + -2.1x = 15.5

Combine like terms: 3.9x + -2.1x = 1.8x
4.6 + 1.8x = 15.5

Solving
4.6 + 1.8x = 15.5

Solving for variable 'x'.

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

Add '-4.6' to each side of the equation.
4.6 + -4.6 + 1.8x = 15.5 + -4.6

Combine like terms: 4.6 + -4.6 = 0.0
0.0 + 1.8x = 15.5 + -4.6
1.8x = 15.5 + -4.6

Combine like terms: 15.5 + -4.6 = 10.9
1.8x = 10.9

Divide each side by '1.8'.
x = 6.055555556

Simplifying
x = 6.055555556