The cost of manufacturing x cases of umbrellas is C dollars (in thousands), where
Monthly production at t weeks is expected to be
I know that = 18(5000+80t)+4sqrt(5000+80t)+9
and that marginal cost or = 28+(2/x^.5)
I'm not sure how to find in order to solve the equation for t=2 in order to find how fast costs are rising per week.