Install GCC / G++ Version 4.9 in Linux Mint

You can get all the upstream development tools for Ubuntu 14.04 (and its derivatives) from ppa:ubuntu-toolchain-r/test

Activate it like so:

sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install g++-4.9

Source: https://wiki.ubuntu.com/ToolChain#PPA_packages

Hope this helps!