En cuanto

En cuanto
 

I think en cuanto means as soon as but I'm not sure.

en cuanto = as soon as
en cuanto a = as for, regarding

So, can you say Hablaré contigo en cuanto te veo. (I'll speak with you as soon as I see you)?

Then If I want to say this phrase En cuanto termine de comer voy al super mercado, the translation would be As soon as I finish to eat , I'm going to the super market.

I don't know if my attempt is accurate but, if you have a better translation, please you correct me, if I'm a wrong like, you must correct me, so I can understand better the kinds and way of translate some sentences in English.

I'm grateful for your help.

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OK. Now I see en cuanto takes the subjuctive. Thank you.

As you correctly stated, this would be:

Hablaré contigo en cuanto te vea.

In a phrase such as «¿En cuánto se los deja el vendedor?» does "en cuanto" still signify "as soon as"? If not, can you explain the meaning of this question?

Thank you in advance.

Just one correction, the subjunctive usage.

Here it means "how much"

How much will the seller ask for it?
(Not sure how idiomatic is this in English, fix it as applicable, but the sense is "how much is the seller going to be asking for it"... after some back and forth...)

This makes sense in the context, as they were bargaining for a price.

Would an appropiate response be somewhere along the lines of «El vendedor se los deja a él en ciento cincuenta pesos.»?

Gracias por su ayuda. <--(Did I write that correctly?)

Yes, and yes. :)

A side note: please note that "¿En cuánto se los deja?" has an accent, and "en cuanto lo vea,..." doesn't. ;)

Right!

(You say "gracias por su ayuda", formally, if you don't know the other person and address him/her politely.)

(You can say "gracias por tu ayuda" if you have familiarity with the person... or in an informal context.)

You may also use "en cuanto" as "about" , specially when you are changing the theme of a conversation:

"-Hemos estado en el nuevo restaurante , y la comida es magnífica.En cuanto al servicio , éste deja bastante que desear."

"-Acabo de firmar todos los documentos. En cuanto a lo del fin de semana..."