The full conversation translates to: (Matilde) Did you go shopping yesterday? (Olga) Yes, I brought two robes.
Looking at this, the verb <em>acheter</em> should be in the <em>passé composé</em>.
The <em>passé composé</em> of <em>acheter</em> following <em>j'</em> is <em>j'ai acheté</em>. (<em>Acheté</em> is the past participle of <em>acheter</em>.)
