Here's another try,
I'm getting screwey results on re-sizing the double chart image.
I chopped the Qchart tool bars off the LHS and had to down size the whole thing a little.
The blue area on RHS is a measure of what was eliminated. The Y axis numbers do look a little smaller to me, but overall readable ???
Have to screw with this some more. Rabbit does this and may be well worth seeing how he does it. The program that I use has so many bells and whistles that I suffer with it. And you don't have it. It did what I needed, 10 or more years ago when I bought it, and I do what I do and never look at the "bells and whistles" It took me almost an hour to figure out how to combine those charts and get them to fit !!
Microsoft photo editor or Paint, you should have, and I think either will get the job done.