DVAT @ 12.50% on the 75% value of the Contract will be charged if you don't maintain the separate acconts for labour and Material.
Service tax will be paid @ 4.80% on the Gross value of the contract , if you are body corporate, otherwise provisions of reverse charge mechanism will be applicable.
There are two more methods under which you can calculate the liability of service tax i.e. on the 40% of the value of the contract you may pay service tax @ 12.36% or under Rule 2(A) bifurcate the value of goods and pay the service tax on remaining amount.