Translation:How much are the violin and the guitar?
Every form of стоить (cost) is stressed wrongly on the second syllable so they sound like the forms of стоять (stand). Misstressing is bery common here in the DL Russian course but this is a real horror because these two verbs are distinguished only by the stress in almost every forms.
Pleeeeeese correct it ASAP! I have reported mistressing problems several times for months but nothing happens.
In English the definite article "the" can never be omitted but there are two cases where there are no articles in indefinite situations. Indefinite plurals (plural and non-specific) or with an uncountable/mass noun that consists of a substance rather than individual components (e.g. sand, fruit).