I'll give you a question, please answer with step-by-step reasoning process.
Isabel has some money in her piggy bank. She spent half the amount and bought a toy. She then spent half of the remaining money and bought her brother a book. If she has $51 left, how much money, in dollars, did she have at first?

204
After buying the toy, Isabel has 51 * 2 = 102 dollars left.

Isabel had 102 * 2 = 204 dollars at first.

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The answer is 204