I'm not sure what you are asking. Is this just about how to Copy/
Paste?

There are 2 ways to copy/paste to get various results.

-You can highlight a part of a formula in the Formula Bar, and then
copy/paste it in there over and over so you don't have to retype a
repetitive section. But you'll have to manually change the parts that
do change. Like in your example, the B and C references change, so
you'd have to go back and retype those.

-You can set references to absolute and relative as needed, then copy/
paste one cell to another to have different sums for different ranges.