Suppose a certain contractor wants to maximize from building one bridge. The contractor uses both labor and capital, and efficient combinations of Labor and capital that are sufficient to make a bridge is by the function If the prices of labor (w) and capital (r) are Birr 5 and Birr 10 respectively. i. Find and interpret the combination of labor and capital that minimizes the firm's cost. ii. Determine the minimum cost of building the bridge. iii. What is the contribution of building additional bridge on the total building cost.