error while instsalling node js and angular js
<pre><code>                sudo apt-get install npm
                       Reading package lists... Done
                       Building dependency tree       
                       Reading state information... Done
                       Some packages could not be installed.This may mean that you have
</code></pre>

<p>requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
                   The following information may help to resolve the situation:</p>

<pre><code>              The following packages have unmet dependencies:
               npm : Depends: nodejs but it is not going to be installed
               Depends: node-abbrev (&gt;= 1.0.4) but it is not going to be installed
               Depends: node-ansi but it is not going to be installed
                  Depends: node-archy but it is not going to be installed
             Depends: node-block-stream but it is not going to be installed
       Depends: node-fstream (&gt;= 0.1.22) but it is not going to be installed
   Depends: node-fstream-ignore but it is not going to be installed
   Depends: node-github-url-from-git but it is not going to be installed
   Depends: node-glob (&gt;= 3.1.21) but it is not going to be installed
   Depends: node-graceful-fs (&gt;= 2.0.0) but it is not going to be installed
   Depends: node-inherits but it is not going to be installed
   Depends: node-ini (&gt;= 1.1.0) but it is not going to be installed
   Depends: node-lockfile but it is not going to be installed
   Depends: node-lru-cache (&gt;= 2.3.0) but it is not going to be installed
   Depends: node-minimatch (&gt;= 0.2.11) but it is not going to be installed
   Depends: node-mkdirp (&gt;= 0.3.3) but it is not going to be installed
   Depends: node-gyp (&gt;= 0.10.9) but it is not going to be installed
   Depends: node-nopt (&gt;= 2.1.1) but it is not going to be installed
   Depends: node-npmlog but it is not going to be installed
   Depends: node-once but it is not going to be installed
   Depends: node-osenv but it is not going to be installed
   Depends: node-read but it is not going to be installed
   Depends: node-read-package-json (&gt;= 1.1.0) but it is not going to be installed
   Depends: node-request (&gt;= 2.25.0) but it is not going to be installed
   Depends: node-retry but it is not going to be installed
   Depends: node-rimraf (&gt;= 2.2.2) but it is not going to be installed
   Depends: node-semver (&gt;= 2.1.0) but it is not going to be installed
   Depends: node-sha but it is not going to be installed
   Depends: node-slide but it is not going to be installed
   Depends: node-tar (&gt;= 0.1.18) but it is not going to be installed
   Depends: node-which but it is not going to be installed
</code></pre>

<p>E: Unable to correct problems, you have held broken packages.</p>