And then we can substitute back right over here. h is equal to 5 over x squared. So all of this business is going to be equal to 20 times x squared plus 36 times x times 5 over x squared. So our cost as a function of x is going to be 20x squared. 36 times 5. Let's see, 30 times 5 is 150. Plus another 30 is going to be 180.