She says she wants to buy a bike every week, as mentioned. She must save $10 every week, which alters the meaning because the author wants you to understand or keep in mind that she must save $10 every week in order to achieve her goal of purchasing a bike every week.
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1 answer
To emphasize this point, the sentence could be revised to say: "In order to ensure she can buy a bike every week, she diligently saves $10 from her weekly budget."