ADDIZIONI E SOTTRAZIONI CON LO STRUMENTO

ESEGUI USANDO LO STRUMENTO
7+3=                            7+3+8=
                                     7+3+3=
7+3+4=                        7+3+1= 
7+3+6=                        7+3+5=                 
7+3+9=                        7+3+7=
7+3+2=                                          
15-3=                            15-6=  
15-2=                            15-8=   
15-4=                            15-7=
15-5=                            15-15=
15-10=                          15-1=