It is not simple addition and multiplication. It is scalar addition. For multiplication also the scalar addition is used. You should learn the scalar addition and multiplication in order to understan this.
Read the basics of scalar addition and multiplication here: https://medium.com/@blairlmarshall/how-does-ecdsa-work-in-bitcoin-7819d201a3ec

I made the calcualtion not manually of course, I used Python script for this (scalar multiplication and addition).

The resulting Point is always has x and y coordinates, but in the showed formula above I used compressed format (prefix 02/03 concatenated with x coordinate). There are 2 wayes to show the point - in compressed format (like was done by me) writing only x coordinate, ot in uncompressed format started with prefix 04 and concatenated with both x and y coordinates.

So, you should learn scalar addition of ECDSA points in order to understand that formula. Also you should be familiar with compressed/uncompressed format of public keys. And do not forget that private key is a number, but public key is a point. Additing one point to another poin you receive a third point. Multiplying point by a number you receive a point.
In ECDSA bitcoin curve you receive the public key of the address as the multiplication of the basis point (G) by a private key (number).

If you do not like to learn and understand all these things by yourself and need a script, write the script parameters and for small bounty I can write it for you.