So that's negative 30 miles per hour. So times negative 30 miles per hour plus 2 times y is 1.6, times dy dt is negative 60 miles per hour. And I'm not writing the units here, but if you were to write the units, you will see that all of our distances are in miles and all of our time is within hours. So we're going to get an answer when we solve for ds dt. That's miles per hour. But I encourage you, if you want to, to actually write out the units and see how they work out. And so this is going to be equal to 2 times s. Well, s is 1 mile, so it's just going to be 2 times ds dt, which is what we're trying to solve for.