Ac restaurant without bar, is regn. required?

Service Tax on Restaurant Service:

A restaurant has got himself registered with the service tax and also VAT. Then how can anyone calculate Service Tax and VAT?

                       Total Bill

(-)                   Abetment

=                    Taxable Service (after abetment) 

(+)                  Service Tax  

=                     Taxable Service+Service Tax

(+)                  VAT.....% on (Taxable Service+Service Tax)                   OR

(+)                  VAT....% on (Total Bill)