23+13= 58-40= 37-7= 18-6=
83+5= 30+48= 16-4= 36+6=
54-5= 17-9= 77-34= 38+7=
45-23= 26+13= 43+25= 66-65+8=
86-(54+6)= 56-20+3=
81+(45-40)= 89-7+7=