a-b=73...........=>b=a-73 a) |___|___|___|___|___|+9=>
a:b=5 rest 9...=> a=b*5+9 b) |___|
---------------------------------- -----------------------------------------
a=?b=? 5b-b=73-9.........=>
4b=64
b=64:4
b=16
a=16*5+9
a=80+9
a=89
89-16=73
89:16=5 rest 9........adica 89=16*5+9
=80+9
=89