You are downloading the Maths Formulas XAP file v18.104.22.168 for Windows Phone. Maths Formulas is a free and useful Education app: MUST HAVE AN APP.Completely Offline & FREE collection of Math Formulas. This is all in one app for math formula. Must try ... You can now download the offline XAP file to install & try it.
Download Locations for Maths Formulas 22.214.171.124 XAP file
Note: To install it manually from an SD card, you should choose one of the server location above to get the offline Maths Formulas XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.