Translation:The shoes don't cost eighteen pesos.
This isn't a critique on the phrase but I just wanted to point out that 18 pesos is equal to 0.89 US dollars. Them some cheap pants
No, shoes is plural, so it should be "don't" or "do not" in Standard English
Because your English verb is incorrect conjugated: For I, you, we, and they use do. For he, she, and it use does.
The shoe does not (or doesn't) cost (third person singular)
The shoes do not (or don't) cost (third person plural)
Would this sentence imply that they are less than 18 pesos? Or just that they're some price other than 18?
Technically, just some other price other than 18 pesos. Though one could certainly expect the subtext of the statement to imply that it is considerably more (not less). :)
'Them' is an object pronoun, not a determiner ('The' is the determiner in this exercise's sentence because it 'introduces' the noun).
Because 'them' is a pronoun, it is used in place of the noun so is never followed by the noun, unlike with a determiner.
Incorrect: I like them shoes
Correct: I like them
Determiner: I like THE shoes, I like THESE shoes, I like THOSE shoes.
All of the examples I have had have mentioned dollars or pesos. Given that we are learning Spanish it would seem appropriate to mention euros since this is the Spanish currency. I have reported it.
Seven Spanish speaking countries use pesos and most (if not all) of Central and some South American (Spanish speaking) countries accept the US dollar as currency. Spain is the only spanish speaking country in the world to use the Euro. In terms of numbers, the choice of these currencies is entirely appropriate.
But that's a bit beside the point - The great thing about learning a language is that it's not just about memorising phrases/sentences as a block without understanding the individual components and grammar. Having that understanding means we can use whichever nouns we wish to suit each context. If we have the vocab, it's up to us. Duo can't input every possible scenario.
I take your point. I 'm not suggesting that Duo doesn't use dollars and pesos just that it would be appropriate to include euros. I have noticedthat in the French tree Duo uses euros but not francs, as far as I can see, even though most francophone countries use a version of the franc. It struck me that there was this difference hence the comment.