So let's just make sure we can understand this. So they're telling us that both x and y are functions. Arguably, they're both functions of t. Y is a function of x, but then x is a function of t, so y could also be a function of t. One way to think about it is if x is equal to f of t, then y is equal to the square root of x, which would just be f of t. Another way to think about it, if you took t as your input into your function f, you're going to produce x. And then if you took that as your input into the square root function, you are going to produce y. So you could just view this as just one big box here, that y is a function of t. But now let's actually answer their question. To tackle it, we just have to apply the chain rule. The chain rule tells us that the derivative of y with respect to t is going to be equal to the derivative of y with respect to x times the derivative of x with respect to t. So let's apply it to this particular situation.