This sentence takes place in a market. So we have two characters. First of all, Randy who is the buyer. The second one is the seller. Therefore the answers are the following:
(1) Correct answer
cuánto
Randy wants to know the price of Papayas. This is a tasty fruit you likely know. So Randy starts with a question ¿cuánto vale? that means how much does it cost? It is important to say that when asking a question the letter a in the word cuánto must have an accent. So:
RANDY: ¿Cuánto vale?
(2) Correct answer
colones
This word is mentioned in the next sentence. What does this word means? Well colones is the plural form of the word colón which is the currency of Costa Rica. Accordingly the papayas cost 300 colones per kg. On the other hand, Costa Rica is a country of central America. So:
VENDEDOR: Trescientos colones.
(3) Correct answer
descuento
This sentence is an affirmation that Randy does when knowing about the price. So the next step Randy takes is to ask for a discount. That is, Randy asks for a deduction from the usual cost of the papayas. On the other hand, the last expression given in question form ¿sí? can be translated as please because this is something like a polite request.
RANDY: Trescientos colones el kilo. Me puede hacer un descuento, ¿sí?
(4) Correct answer
vale
vale is the conjugation of the verb valer for the third person singular in the simple present. This verb translates in this context as to cost. So the seller tells Randy that the cost of the papayas is cuatro ochenta... cuatro y medio. We use the simple present tense to talk about habitual actions or routines. This tense is also used to describe things that happens now or in the near future. It is also used to talk about universal truths, facts, lapses of time, and when ordering in restaurants and stores.
VENDEDOR: OK... Vale cuatro ochenta... cuatro y medio.
(5) Correct answer
cuarenta
In this point, you can realize that the bargaining has begun. So cuarenta represents the number forty in English. Lastly, the price of the papayas remains in cuatrocientos cuarenta, that is, this number represents four hundred forty in English. So we can say that Randy reached to buy the papayas for cuatrocientos cuarenta colones Costa Rican
VENDEDOR: Cuatro cuarenta.