And so you hire a bunch of consultants to come up with what your cost is as a function of x. What your cost is as a function of x. And they come up with a function. They say it is the number of the thousands of pairs you produce cubed minus six times the thousands of pairs you produce squared plus 15 times the thousands of pairs that you produce. And once again, this is going to be, this is also going to be in thousands of dollars. Now, given these functions of x for revenue and cost, what is profit as a function of x going to be? Well, your profit as a function of x is just going to be equal to your revenue as a function of x minus your cost as a function of x.