Step 3: Describing how temperature changes over time. The temperature changes at a rate proportional to the sum of (1) the influence of every-thing other than the daisies, which is captured by the variable p, and (2) the influence of the daisies. The influence of the daisies will be linearly proportional to their density, giving us the following differential equation, dtdy=p+rn where r is a constant that describes the amount of influence that the daisies have. We'll assign this parameter a value of r=10, which can be interpreted as saying that when the daisies are at their maximum possible density, they bring the global temperature down by 10 degrees..