345. In a gas chromatographic analysis of a product for toluene content, p-ethyltoluene was used as an internal standard. Initially, a standard mixture containing (mass) toluene and p-ethyltoluene was analyzed, and chromatographic peaks of 4.70 and 4.20 cm in height, respectively, were obtained. When analyzing the product, 0.045% (mass) of the standard was added to the sample, and a chromatogram was obtained in which the peak heights of toluene and p-ethyltoluene were 5.21 and 4.11 cm, respectively. What is the mass fraction (%) of toluene in the sample?

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