Each unit sells at $p = 60 - 2x$ rupees when $x$ units are sold. At what price is the total revenue greatest?

Explanation

1. 01

   $R(x) = 60x - 2x^{2}$, and $R'(x) = 60 - 4x = 0$ at $x = 15$.

2. 02

   The price there is $60 - 30 = 30$ rupees.