The Symbolab app worked for me on iPhone 4 iOS 7.x.x
I downloaded de app/ipa thru iTunes , I downloaded the latest version on my Mac thru iTunes this version isnt compatible with my iOS , so I installed an older version thru the App Store on the iPhone , I am logged on iTunes with the same account im logged on the iPhone
The iPhone showed me a cloud instead of install because I already downloaded the app on my Mac thru iTunes ,so after I hit on it ,it said that I needed an older version and was able to download it .
The path to replace the archive is Symbolab/Library/Preferences for me , im using ifunBox
Sorry for the english
Thanxx