What is the answer with steps

Late at night some traffic signals change patterns and become ?

How many liters of 60% alcohol solution should be added to 40 liters of a 20% alcohol solution to make a 50% solution?

When looking at research about instructional strategies, make sure the research is a. from peer-reviewed studies. b. approved by state and federal government organizations. c. online and easily accessible. d. about the same topic you're interested in.