Mark M. answered 07/30/19
Retired college math professor. Extensive tutoring experience.
a). Revenue = (price)(quantity)
So, R(x) = (-1/10 x + 800)(x) = (-1/10)x2 + 800x
b). Profit = Revenue - cost
P(x) = R(x) - C(x) = (-1/10)x2 + 720x - 6000
c), The graph of y = P(x) ix a parabola opening downward. P(x) is maximized when x is the x-coordinate of the vertex. So, maximum profit when x = -(720) / (2(-1/10)) = 144.
d). Profit is maximized when p = -(1/10)(144) + 800 = $785.60