How to DSUMPRODUCT?

I have a table that has the following layout, and is quite long.

Quantity    Price5           1014          510          7.5

I need to get the sum of the product of each line. Unfortunately, I can't use the sumproduct() function and necessarily have to use Google Sheets Database functions (DSUM, DPRODUCT, etc). [because of filtering and the need to refer to columns by name].

How can I emulate a sumproduct() using Google Sheets D functions?