Check out example codes for "HOW TO CALL AN EXTENSION METHOD FOR VIEW C#". It will help you in understanding the concepts better.
Code Example 1
<pages>
<namespaces>
<add namespace="System.Web.Mvc" />
<add namespace="System.Web.Mvc.Ajax" />
<add namespace="System.Web.Mvc.Html" />
<add namespace="System.Web.Routing" />
<add namespace="System.Linq" />
<add namespace="System.Collections.Generic" />
<add namespace="MyProject.Extensions" />
</namespaces>
</pages>
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