Science:Math Exam Resources/Courses/MATH104/December 2012/Question 04 (c)/Hint 1

Here we are given that

${\frac {dR}{dt}}=0.15$

as well as $p=4$ and from computations in the first part, we know that $q=2$. We seek to find ${\frac {dp}{dt}}$. What's the relationship between revenue, price and quantity?