Can somebody tell me what theme means

12. why do you think that using a conversational tone with plain language when writing businesses messages is a good idea?

The best way to become a good writer is to

Which sentence is punctuated correctly? the shoes normally cost 40 dollars, however; we got them on sale. the shoes normally cost 40 dollars however we got them on sale. the shoes normally cost 40 dollars, however, we got them on sale. the shoes normally cost 40 dollars; however, we got them on sale.