（1）1.56x+3.16 =7.84  

                  1.56x=4.68

                        x=3（2）7.6x+2x+0.72 =18 

                        9.6x=17.28

                            x=1.8（3）5.8 ×4.5 +0.4x =29.1

                         0.4x=3

                              x=7.5

（4）x +0.7x+0.96 =3

                      1.7x=2.04

                          x=1.2（5）3.9x +9.36 =13.65

                   3.9x=4.29

                       x=1.1（6）（x-3）÷4=7.2

                     x-3=28.8

                        x=31.8