Write an Excel formula?

Question

excel

Good evening!
Please help me to make a formula for Excel, I didn't manage to make it myself :)
I need to sum the cells opposite from the adjacent column by coincidence from one cell. For example, if in column O there are matches in cells O2, O4, O5, then find the sum of the digits in the cells opposite, in column N (respectively N2, N4, N5).

Answer 1

If I understand the essence correctly, then this can be done like this:
https://1drv.ms/x/s!AjAPFTiQ4P6Lkso6tI1ofKzrT7V8BA
The formula for D2 is as follows: {=SUM(IF($A2:$A7=D1;$B2:$B7;0 ))}, note that this is an array formula