This is just showing you how to use a mole of anything (in this case carbon atoms).
Equation
Set up a proportion for solution.

Notice that the two units that are the same will eventually cancel out and you will be left with grams.
Solution
Multiply both sides by 3.48 * 10^25

Cancel out the powers and units that can be cancelled.
3.48*10 * 12.01 / 6.02 = x
Solve for x
x = 69.42 grams