Determine the empirical formula for compounds that have the following analyses. a. 28.4% copper, 71.6% bromine b. 39.0% potassium, 12.0% carbon, 1.01% hydrogen, and 47.9% oxygen c. 77.3% silver, 7.4% phosphorus, 15.3% oxygen d. 0.57% hydrogen, 72.1% iodine, 27.3% oxygen