（1）3.2x-9.8=9.4

               3.2x=19.2

                   x=6

  （2）3x+0.3×4=1.74

              3x+1.2=1.74

                     3x=0.54

                        x=0.18（3）4（x-0.8）=9

                 x-0.8=2.25

                       x=3.05