But the question asks us, write the second derivative in terms of W. But lucky for us, we know how to express this as a function of W. They gave that to us in the problem. This was given. This is just me rewriting it in a different notation. So this is going to be the same thing as 1 over 25 times the derivative of W. And the derivative of W is this. The differential equation literally tells us the derivative of W is this over here. So 1 over 25 times 1 over 25 WT, or the function W as a function of T, minus 300. And so we can say the second derivative of W as a function of T is equal to 1 over 625 times W as a function of T, which is a function of T, minus 300.