Could I Show "SUM(field_a) / SUM(field_b)" value in report?

[TI5]

Suppose that there are the following records in pm_project_task table.
(field_for_groupby, field_a and field_b are custom field.)

field_for_groupby	field_a	field_b
GroupA	83	91406
GroupA	39	91302
GroupA	84	2598
GroupA	26	97044
GroupA	10	77695
GroupB	3	91406
GroupB	5	91302
GroupB	2	2598
GroupB	7	97044
GroupB	2	77695

I would like to display the value of "SUM(field_a) divided by SUM(field_b)" in the report.

However, the report designer has only the following items in the aggregation options.

What should I do ?

=====

I've added some information. 

If the value I want to display is expressed in SQL, it will be as follows.

SELECT SUM(field_a) / SUM(field_b) FROM pm_project_task GROUP BY field_for_groupby

[Allen Andreas]

Hello,

You'd have to consider creating a function field: https://docs.servicenow.com/bundle/sandiego-now-intelligence/page/use/reporting/concept/function-fie...

Please mark reply as Helpful/Correct, if applicable. Thanks!

[TI5]

Thank you for reply !

You can add a value to other field within the same record, but you can't seem to add a value to a field of the other record.

Please excuse my lack of explanation. 

If the value I want to display is expressed in SQL, it will be as follows.

SELECT SUM(field_a) / SUM(field_b) FROM pm_project_task GROUP BY field_for_groupby

[Allen Andreas]

Hello,

I'm sorry, your reply doesn't make any sense to me.

I don't know if you're replying to me meaning you're trying to use a function field, as I mentioned, which if so, would be helpful.

Otherwise, I don't know if you're telling me something else you're trying to do.

Please mark reply as Helpful/Correct, if applicable. Thanks!

[TI5]

If the value I want to display is expressed in SQL, it will be as follows.

SELECT SUM(field_a) / SUM(field_b) FROM pm_project_task GROUP BY field_for_groupby