Is it possible to pass variable from parent build.gradle to child build.gradle?

Hello all, i am new to gradle and i run into a problem where i want to define a plugin version into parent build.gradle file and pass it to childs

Or is it possible to declare all dependencys in parent build.gradle file and than from child say that it want use specific dependency from parent ?

I recommend reading the multi project build section in the userguide: http://www.gradle.org/docs/current/userguide/multi_project_builds.html