One benefit of Line Bar Combo graphs is that they permit the bars and lines to have different value scalesone on the right side of the graph and one on the left. This is especially useful when you want to compare two data sets with different ranges. The category labels along the bottom of the graph will be the same for both the lines and the bars. However, the left and right scales can have the same or different ranges.
You can also manually set the number of series that will be used for lines or bars. To do this, go to the General pane in the Graph Properties, check on Manually Set Number of Lines, and type the number of data series you wish to be displayed as lines in the Number of Lines box. The graph will then display the first n data series as lines, where n is the number you typed. All other data series will appear as bars.