Repeating the same formula across rows and create a sum total

I would like to repeat the same formula across multiple rows and then calculate a total sum. Eg. for each row I would like to sum the number of days and multiply that with a day rate and then calculate the total sum for all rows. Currently, I am manually changing the references for each row, but I was hoping I could create the formula once and then pass an array of the rows instead

>Solution :

You may try:

=sumproduct(B3:B8,byrow(D3:F8,lambda(Σ,sum(Σ))))