1) 45-42,6=2.4

2)2.4*3.3=7.92

3) 9:7.5=1.2

4)7.92+1.2=9.12

   45                        2.4           90   :  7.5                        7.92

 - 42,6                   *3.3           75   -----------               +  1.2

---------              -----------     -----------  1.2             -----------------

     2.4                     72           150                                  9.12

                             72             150

                       --------------   ----------

                            7.92               0