79.70 grams
First, calculate the molar mass of Na2CO3 by looking up the molar mass of the elements used in it.
Sodium = 22.989769
Carbon = 12.0107
Oxygen = 15.999
Multiply each molar mass by the number of atoms used, and sum the results to get the molar mass
2 * 22.989769 + 12.0107 + 3 * 15.999 =105.9872
Finally, multiply the molar mass by the number of moles you need.
0.752 * 105.9872 = 79.7024 grams