Solving for the missing length of a segmented right triangle

Solving for the missing length of a segmented right triangle

Screen Shot 2015-07-28 at 12.17.11 PM.pngEssentially I have no idea where to even start on this. I know I’ve done it before back in highschool, but I’m not entirely sure what to do or where to start. Help would greatly be appreciated because my textbook covers nothing on the subject, and no one else is replying on the usual student discussion forums.