A widget manufacturer has an infinitely substitutable production function:

Q = K + 2L.

a. Graph the isoquant for Q = 20. What is the MRTS (marginal rate of technical substitution of L for K) along this isoquant?

b. If the wage rate (w) is $1 and the rental rate on capital (r) is $1, what cost minimizing combination of K and L will the manufacturer employ to produce an output of 20?

c. How would your answer to part b. change if w rose to $3 with r remaining at $1?