5.5x-1.3x=12.6 3.85+1.5x=6.1 6x-0.9=4.5 4×4.5-3x=6.33.

问题描述:

5.5x-1.3x=12.6                 
3.85+1.5x=6.1
6x-0.9=4.5                    
4×4.5-3x=6.33.

5.5X-1.3X=12.6,         4.2X=12.6,    4.2X÷4.2=12.6÷4.2,            X=3;  ...