The patient's temperature went from 105.85 to 99.1. That is a decrease of 6.75 degrees. You want to find the temperature decrease per milligram, which can be found by dividing the temperature by the number of mg of the drug.
6.75 / 5 = 675 / 500 = 1.35
So, the rate at which her temperature decreased per milligram is 1.35 degrees per mg.
