I have a simple single bar graph
X = department
Y = Average age of open transactions
What I would like to do is have the total count of transactions as the data label in each bar.
If the data isn't included in the graph I don't believe you can have that as a data label. See if you can alter the graph in a way to include transaction counts in it that you can then use to visually see the count.
Line + Bar Graph.
Y - avg age of open trans
Line (above the bars) shows total transactions by department. Then you could see all the data you're asking for