How to combine two graphs with the same data source into one graph

Hi everyone,

Am working on a project which requires combining two graphs with the same data source into one graph.

Details are as follows.

There are three tables. Table Dept, Table A, and Table B.

Based on the tables and data above, I have already created Graph 1 and Graph 2.

Graph 1, grouped by the Dept column of Table Dept, shows the amount difference of each dept (total amount of each dept from Table A minus total amount of the corresponding dept from Table B).

Graph 2 is a compound bar graph, also grouped by the Dept column. It shows the total Amount of each Dept from Table A and Table B.

The problem I am facing is creating Graph 3 which is a joint graph of Graph 1 and Graph 2.

The image of Graph 3 is attaced below.

Anyone with good ideas?

If any further information is needed pls feel free to contact.

Thank you very much.