Complex sentence: However, both the cost and the realistic implementation of this ideal has been a problem: the Khan Academy might have successfully adress these issues, through both cost-free nature of the site and its wide accessibility via the internet.
Split into simpler sentences: However, both the cost and the realistic implementation of this ideal has been an issue. Some promote that the Khan Academy has addressed these issues, through both cost-free nature of the site and its wide accessibility via the internet.