They have zero as the lower bound. So what we could do, we could rewrite this. This is the same thing. This is equal to negative six minus, if you swap the bounds of integration, you've swapped the sign on the integral. So we could say minus from negative three to zero of f of t dt. And now this thing right over here, this expression right over here, is the area under this quarter circle. And the area under this quarter circle, we can just use a little bit of geometry to figure that out.