Now we substitute our function of x back into our equation for u and w In 9x 1 1 C x Step 6 Now we know the fixed costs are 250 Thus we have the following C 0 250 Plugging this into the cost function we can find K 250 C 0 n 9 250 1 K 250 1 K In 9x 1 K 2251 X 1 K