Answer:
3750/ (x + 15)^2.
Step-by-step explanation:
We use the quotient rule:
If f(x) = u/v then f'(x) = (v du/dx - u dv/dx) / v^2
So here the derivative is
(x + 15) *250 - 250x * 1) / (x + 15)^2
= (250x + 3750 - 250x) / (x + 15)^2
= 3750/ (x + 15)^2.