I need help with a titration problem, thanks so much?

Aspirin (C9H8O4) is an acid which can be titrated with a base to determine purity. If an aspirin tablet weighing 0.732 g is titrated with standardized 0.1345 M KOH, the endpoint is reached after 28.24 mL of KOH have been added. What is the percentage of aspirin in the tablet? The acid/base ratio is 1:1.
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