5x + 10 - 3 = 12 8 - 2x + 15 = 7 4x + 6 - 1 = 17 12 - 3x + 20 = 5 7x + 1...

1：运行安装命令rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.n...