Parser Error Message: Could Not Load File Or Assembly System

I am getting this error for one of my website. This site is working fine on the old server from which it has been migrated:

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Server Error in '/' Application.
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Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.
Parser Error Message: Could not load file or assembly 'System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified. (c:Inetpubvhosts<domain.com>httpdocsweb.config line 59)
Source Error:
Line 57: <add verb="GET" path="CrystalImageHandler.aspx" type="CrystalDecisions.Web.CrystalImageHandler, CrystalDecisions.Web, Version=10.2.3600.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/></httpHandlers>
Line 58: <httpModules>
Line 59: <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
Line 60: </httpModules>
Line 61: </system.web>
Source File: c:Inetpubvhosts<domain.com>httpdocsweb.config Line: 59
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Version Information: Microsoft .NET Framework Version:2.0.50727.3053; ASP.NET Version:2.0.50727.3053
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I am attaching the web.config file as attachment. Can anyone tell me how do I fix this.