Could anybody explain why these two lines give different outputs for the
inline elisp calculation?

First line:

@@latex:\fbox{@@ src_emacs-lisp{(setq var-Q1 (string-to-number (calc-eval "evalv(15.357*(184.2-80))")))} @@latex:}@@

Second line:

@@latex:\fbox{@@ src_emacs-lisp{(setq var-Q1 (string-to-number (calc-eval "evalv(15.357*(184.2-80))")))}@@latex:}@@

The only difference in these two lines is a space before the last LaTeX
directive.

Screen shot attached.