The equation is that of a parabola, meaning that the maximum (or sometimes minimum) is 1/2 the sum of the solutions found using the quadratic equation.
y = 0 for the 2 solutions to {-b +/- sqrt[b2 - 4ac]} / 2a, where a = -3, b = 152 and c = -1150 from the equation for y. Plug a, b and c into the quadratic formula to get x = 9.2571 and x = 41.4095 as the 2 solutions.
9.2571 + 41.4095 = 50.6666... and the midpoint is 25.3333...
When x = 25.3333..., y = 775.33333.....
To the nearest cent, x=25.33 results in a profit of 775.33.
When x=25.25, Y = 775.31
When x=25.4, Y = 775.32
These are both less than 775.33 when x = 25.33.