Shift + Ctrl + Alt + R

Then follow the prompts :)

Tech Help Sheets Portrait.pdf

How to Screen Capture on a Chromebook

How to take a picture with a Chromebook.webm

How to Take a Picture with a Chromebook

How to take a picture or video on your Chromebook and find the file.pdf

Ctrl+Shift+T  Retrieve a closed tab

Alt+0247 Type a division symbol