Abrí la válvula e inflé la cámara de aire.

They are both in the preterite tense, first person singular: I opened and I inflated.

So:

• abrí = I opened
• inflé = I inflated / I blew up

The preterite is used here because these are completed actions in the past.

Spanish often drops subject pronouns when the verb form already makes the subject clear.

• abrí already tells you the subject is I
• inflé also tells you the subject is I

So Yo abrí la válvula e inflé la cámara de aire is possible, but yo is normally unnecessary unless you want emphasis or contrast.

This is a very common Spanish spelling-and-sound rule.

Normally, and is y, but it changes to e before a word that begins with an i sound, to avoid an awkward repetition of similar sounds.

So:

• padre e hijo
• España e Italia
• abrí la válvula e inflé...

Since inflé begins with an i sound, y becomes e.

They are there for different reasons.

• abrí and inflé have written accents because they are preterite first-person singular forms ending in -í and -é.
• válvula and cámara have accents because their stress pattern does not follow the default pronunciation rules.

These accents are part of the correct spelling and also help distinguish pronunciation.

In Spanish, it is very common to use the definite article (el, la, los, las) where English might use the, a, or sometimes no article at all.

Here, Spanish treats these as specific objects involved in the action:

• la válvula
• la cámara de aire

This sounds natural in Spanish. Omitting the article would usually sound wrong here.

It is a noun phrase made of:

• cámara = chamber / tube
• de aire = of air

So literally it is something like air chamber, but in normal usage it often refers to an inner tube or inflatable tube, depending on context.

This is a common Spanish structure:

• X de Y = X of Y

For example:

• botella de agua = bottle of water
• gafas de sol = sunglasses

Spanish very often uses noun + de + noun where English might prefer a compound noun or adjective.

So cámara de aire is the natural expression, not normally cámara aérea in this context.

Compare:

• motor de gasolina = gasoline engine
• mesa de madera = wooden table
• cámara de aire = inner tube / air tube

Yes. Inflé is the yo form of the preterite of inflar.

Basic forms:

• infinitive: inflar
• present: inflo = I inflate / I blow up
• preterite: inflé = I inflated / I blew up

It is a regular -ar verb in this tense:

• inflé
• inflaste
• infló
• inflamos
• inflasteis
• inflaron

Because abrir is an -ir verb, while inflar is an -ar verb.

In the preterite:

• regular -ar verbs take endings like -é, -aste, -ó
• regular -er/-ir verbs take endings like -í, -iste, -ió

So:

• inflar → inflé
• abrir → abrí

Both are regular here; they just belong to different verb groups.

In standard Spanish, before a word beginning with an i sound, y normally changes to e, so e inflé is the preferred and correct form here.

Using y inflé would sound unnatural or incorrect in careful standard Spanish.

So the normal version is:

• Abrí la válvula e inflé la cámara de aire.