（1）x÷0.26=0.52

 x÷0.26×0.26=0.52×0.26

                   x=0.1352

  （2）9x﹣2x=21.7

                  7x=21.7

             7x÷7=21.7÷7

                    x=3.1

（3）3.18×2﹣2x=4.26

              6.36﹣2x=4.26

                         2x=6.36﹣4.26

                    2x÷2=2.1÷2

                          x=1.05

 （4）0.25x+3.75=12

0.25x+3.75﹣3.75=12﹣3.75

           0.25x÷0.25=8.25÷0.25

                           x=33