Excel formula: If condition then do that condition

Some excel IF statements can get fairly long, and I am looking for an easier way to writ them. For example, if I were to write:

If($B$4+13=7,$B$4+13,FALSE)

I think it would be easier to put:

If($B$4+13=7,[Do the left hand side of the equation without making me re-type it], FALSE)

Especially if the condition is very long and complex.

Is there something I could write in place of:

[Do the left hand side of the equation without making me re-type it]

Thanks!