calculer en regroupant les astucieusement les termes: (-34.2)+25.7-(+25.8)-(-35.2) -2.8+6.4-7.2+5.6 67.43-(-32.57)+(-45.68)+35.68

(-34.2)+25.7-(+25.8)-(-35.2)

-34.2+25.7-25.8+35.2=

       8.5    -25.8+35.2=

             -17      +35.2=

                 18.2  

-2.8+6.4-7.2+5.6=

     3.6   -7.2+5.6=

        -3.6     +5.6=

                2

67.43-(-32.57)+(-45.68)+35.68=

67.43+32.57-45.68+35.68=

   100          -45.68+35.68=

            54.32        +35.68=

                   90

-34.2 + 25.7 - 25.8 +35.2 = 35.2-34.2-25.8+25.7 = 1-0.1=0.9

-2.8+6.4-7.2+5.6=-7.2+6.4+5.6-2.8=2

67.43+32.57-45.68+35.68=100+35.68-45.68=90