.
When the problems comes in such a formulation, presenting the revenue function as th product of two linear binomials,
the problem can be easily solved mentally.
The roots of the quadratic function R(x) = (300-15x)(5+0.50x) are = 20 and = -10, OBVIOUSLY.
The maximum value of the parabola is achieved exactly half way between the roots, at x = = 5.
So, maximum revenue is achieved at 5 increments by $0.50 from $5, i.e. at the ticket price of 5 + 5*0.5 = 7.5 dollars,
and the value of the maximum revenue is then
= (300 - 15*5)*(5 + 5*0.5) = 1687.50 dollars,
comparing with 300*5 = 1500 dollars without optimization.