とりあえず以下を打っておけばOK!!!
$ sudo yum update -y
$ sudo yum groupinstall -y "Web Server" "MySQL Database" "PHP Support"
$ sudo yum install -y php-mysql
$ sudo service httpd start
$ sudo chkconfig httpd on
$ chkconfig --list httpd
$ sudo groupadd www
$ sudo usermod -a -G www ec2-user
$ exit
$ groups
ec2-user wheel www
$ sudo chown -R root:www /var/www
$ sudo chmod 2775 /var/www
$ find /var/www -type f -exec sudo chmod 0664 {} +
$ yum list installed php
$ sudo yum install -y php
$ sudo service httpd restart
$ sudo service mysqld start
$ sudo mysql_secure_installation
$ sudo service mysqld stop
$ sudo chkconfig mysqld on