Va rog urgent dau coroană

Explicație pas cu pas:
a) 42:2=(40+2):2=
=(40:2)+(2:2)=
=20+1=21
39:3=(30+9):3=
=(30:3)+(9:3)=
=10+3=13
88:2=(80+8):2=
=(80:2)+(8:2)=
=40+4=44
b) 88:4=(80+8):4=
=(80:4)+(8:4)=
=20+2=22
96:3=(90+6):3=
=(90:3)+(6:3)=
=30+2=32
66:2=(60+6):2=
=(60:2)+(6:2)=
=30+3=33
c)99:9=(90+9):9=
=(90:9)+(9:9)=
=10+1=11
82:2=(80+2):2=
=(80:2)+(2:2)=
=40+1=41
36:3=(30+6):3=
=(30:3)+(6:3)=
=10+2=
=12