Cuando intento instalar php5 en Ubuntu 16.04 usando el siguiente código:

sudo apt-get install php5 php5-mcrypt

Me sale el siguiente error:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package php5 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'php5' has no installation candidate

He intentado reinstalar pero no ayuda.

Todo este error se encontró después de actualizar mi Ubuntu 15.10 a 16.04