And this right over here is going to be the definite integral from zero to 10. B prime of t, they give it to us right over here, is negative 13.84 e to the negative 0.173 t dt. And now we just evaluate this. So we can, let's take the, well, we can evaluate this. What we have to do is, because we know that the derivative, we know the derivative of e to the ax is a e to the x. Let me write that. The derivative of e to the ax is equal to a e to the ax, just from the chain rule, derivative of the inside is just a, and then we multiply that times the derivative of the entire thing, and derivative of e to the x is just e to the x.