Gst bill cess

shabaz a (47 Points)

26 September 2019  
I have recieved a bill of steam coal

which he has added additional cess 400 rd per tonne which 10212.
so now my question is.. how should I calculate cess on coal..
I mean if I calculate on per ton the amount will be same..
if calculate on rate. it will calculate huge.. amount.. so please clarify..