Answer :
x=quantity produced or sold.
Average cost = c(x)/x = (3700+5x-0.04x^2)/x = 3700/x+5-0.04x
Marginal cost = c'(x) = 5-0.08x
Average cost = c(x)/x = (3700+5x-0.04x^2)/x = 3700/x+5-0.04x
Marginal cost = c'(x) = 5-0.08x