It's negative, let me do that same color. It's equal to negative 16 times one minus 0.1t. So what's this going to be? What is the rate of change of the number of words known per day two days after studying for the test? Well, we just have to evaluate this when t is equal to two. So w prime of two, do that in magenta. W prime of two is going to be equal to, whoops, I'll just go with the magenta, is equal to negative 16 times one minus 0.1 times two.