Final answer:
Country L should use the new technology because it requires fewer inputs and would pay at most the difference in costs to acquire it.
Step-by-step explanation:
Country L should use the new technology because it requires fewer inputs of both capital and labor compared to the current technology. The new technology uses K=9 and L=4 as inputs, while the current technology uses the same level of production (Y=6) but with lower wages and capital. Country L would pay at most the difference in costs between the two technologies to acquire the new technology.