installing python

[emaraiza98 at gmail.com]

I installed pycharm for a computer science class, and installed python 3.5.2. However, my computer won't accept 3.5.2 so my teacher told me to install an earlier version to change the project interpreter. I did but when I tried to open python with pycharm it said that the "SKD is invalid". I don't know what I'm doing wrong and I have to have everything installed and running by Wednesday.