A scientist needs to make 5.4 liters of saline solution (salt water), in which the salt level must be at 28% concentration (meaning 28% of the water is salt). Unfortunately, the scientist only has two types of saline solution in his possession. He has saline solution with a 12% concentration level and saline solution with a 30% concentration level. How much of each type of saline solution should the scientist mix together to achieve 5.4 liters of saline solution at a concentration level of 28%?