And just so that we have some variables in place, let's call this distance s. So what we really are trying to figure out is right at this moment, what is ds dt going to be equal to? Well, let's think about what we know that we could use to somehow come to terms or figure out what ds dt is. Well, we know the distance of the car and the intersection. And let's just call that distance y. So y is equal to 0.8 miles. We also know that d, so let me write this. We know that y is 0.8 miles right now.