Read the passage and answer the question. Passage: "Alexa had been saving her pocket money for three months. She wanted to buy a birthday present for her mother. When she finally counted the coins and notes in her piggy bank, she had exactly fifty dollars. She went to the bookshop and chose a beautiful journal with a floral cover. She paid for it herself and wrapped it carefully with gold ribbon." Question: Why did Alexa save her pocket money?