First find how much sodium the parmesan has in total by multiply the amount of sodium per ounce by the number of oz: 25 mg/oz * 8 oz = <<25*8=200>>200 mg
Then use the same process to find how much sodium is in the salt: 50 mg/tsp * 2 tsp = <<50*2=100>>100 mg
Then find the total sodium in the recipe by adding the sodium from the cheese and the salt: 100 mg + 200 mg = <<100+200=300>>300 mg
Then multiply the total amount of sodium by 1/3 to find how much less sodium James wants: 300 mg * 1/3 = <<300*1/3=100>>100 mg
Then divide this amount by the amount of sodium per ounce of cheese to find how many fewer ounces of cheese he needs: 100 mg / 25 mg/oz = <<100/25=4>>4 oz
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