This isn't as much a math problem as it is just a problem about basic chemical concepts. In order to solve it all you have to do is recognize that 6.02 x 10^23 is Avogadro's number, in other words the number of atoms or molecules contained in one mole of any substance. So since the amount of copper that you have has 6.02 x 10^23 atoms of copper in it, it must mean that you have a mole of copper. Meaning that 63.5g is the molar mass of copper. Therefore all you have to do is remember what the definition of a mole is or how to find the molar mass of a substance to realize that if the molar mass of copper is 63.5g, the atomic mass of copper must be 63.5 amu. If you really wanted to do this arithmetically you'd have to convert grams into amu by first converting grams to kilograms and then dividing the resulting kilogram value by 1.66 x 10^-27 which will give you the mass in amu, which you will then have to divide by 6.02 x 10^23 to find the mass of each individual atom in amu.
Edit: I believe either you or the person who originally came up with the problem meant to say 63.5 instead 6.5 since 6.02 x 10^23 atoms of copper is a mole which would weigh 63.5g not 6.5g.
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