Complex sentence: You should not mix up Net assets in comparison with "Return On Net Assets" (RONA) is a measure of financial performance of a company and calculated as net income divided by fixed assets plus working capital.
Split into simpler sentences: You should not mix up Net assets in comparison with "Return On Net Assets" (RONA). RONA is a measure of financial performance of a company and calculated as net income divided by fixed assets plus working capital.