Arshad,

Please remember that this is a users forum - a best efforts by the community, for the community.

James suggested that you try searching the forum.  If you type in "transform" to the search box then you get pages of entries on transforms.  You need to do a little more searching rather than just trying to bump your initial question.

Try docs/DOC-2554 - there is certainly an example in there that does arithmetic on event attributes.

Cheers,

Jane