Let a firm's production function be F(K, L) = 3K + 2L where K is the amount of capital and L is the amount of labor employed by the firm. Let the unit prices of capital and labor be given by, respectively, r = $6 and w =$5. Based on this information, please characterize the optimal (cost minimizing) allocation of inputs for the level of output Q=90. Please illustrate your solution graphically.