Hi @a_d - Thanks for confirming.

Here is a good example.

I've also tested it and given some snapshots below if it helps. My data looks something like the below.

You can see above the results (on the right side) an option to create a custom calculation. In the editor, add the formula. SUM(sales) / SUM(orders)

You can then build the visualisation and choose the custom measure you have created. 

Hope that helps!

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