18--10=
the two negative signs make a plus so you simply have 18 + 10 which is 28
Top right would be rhombus
I got 20,737 but I could be wrong so I will attach my algorithm and work.
20 divided 100 = .2 then u multiply 16.5 by .2 =3.3 then u subtract that from 16.5 and u get 13.2