How to solve installation error, while installing tomcat

I got an error while installing tomcat 7. I have searched for it, but couldn't find any solutions.

The error is..

  Reading package lists... Done
  Building dependency tree       
  Reading state information... Done
  E: Unable to locate package tomcat 7

Please help me...

Solution

Looks like you have a space between tomcat and 7. Use the following command to install tomcat7: sudo apt-get install tomcat7

[Update]
1. Add deb http://security.ubuntu.com/ubuntu trusty-security main universe to /etc/apt/sources.list file.
2. Run sudo apt-get update
3. Run sudo apt-get install tomcat7