Solution: 3x-0.9+0.9=2.4+0.9.

3x=3.3

3×3 = 3.3×3

x= 1. 1

Solve the equation according to the "properties of the equation", that is, both sides of the equation add (or subtract) the same number at the same time, and both sides of the equation are still equal. Similarly, if you multiply (or divide) the same number on both sides of the equation at the same time, both sides of the equation are still equal. Note: Except 0.