What is the average atomic mass of 38 atoms of Copper-65 and 92 atoms of Copper-63?

Copper has two naturally occurring isotopes, ${ }^{6} \mathrm{Cu}$ (isotopic mass $=62.9296 \mathrm{amu}$ ) and ${ }^{65} \mathrm{Cu}$ (isotopic mass $=64.9278$ amu . If copper has an atomic mass of 63.546 amu, what is the percent abundance of each isotope?

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