Green’s Dictionary of Slang

(orig. US business) to sum up, to speak succinctly.

1984		Scientific American Sept. 114: I wanted to bottom line what’s going to make Zapata! the hottest selling all-sport shoe in our line [HDAS].
1989		CBS This Morning 5 Aug. [CBS-TV] And let me bottom-line this for, you Kathleen [HDAS].
2017		S.M. Jones August Snow [ebook] ‘Botton-line it for me [...] In English’.