Can I program using inheritance in SoloLearn?

Answer 1

You can use inheritance in sololearn, but it's bad idea. It's better to use sololearn in small projects, like projects using math or design.
When you want make the best project using oop or something else - use ide specialised on java(i mean ide like "processing". I don't work with java, so I know only this ide).

Answer 2

yes you can, (especially as exercise)