Table.Group and complex aggregation function

[Taurus]

For example, I have this simple SQL statement:

SELECT a, SUM(b)*a  FROM table  GROUP BY a

How can I implement "SUM(b)*a" in a Table.Group function? For "SUM(b)" Power Query generates "each List.Sum([b])", but how to multiply this by "a" ? Or how to implement SUM(b*a), which cause the same result?

[PhilC · Accepted solution]

Can you Group by [Column a], with a sum aggregation for [Column b], then add a custom column for [Column a] * [new column b]?