Merge two sets of graph into one graph on excel?

I have two sets of data, both having same x-axis and y-axis variable. I created two line-data charts for both of these data. However, my professor wants us to merge these line-data charts into one single chart, so we can compare each point on the line.

I have no idea how to merge the graphs or how to have two series in one graph.
I would really appreciate it if someone can help me here.