Update chapters/operatorsandexpressions.tex

Co-authored-by: Elena Shmoylova <eshmoylova@users.noreply.github.com>

chapters/operatorsandexpressions.tex

@@ -1417,7 +1417,7 @@ \section{Variability of Expressions}\label{variability-of-expressions}
 
 \subsection{Function Variability}\label{function-variability}
 
-The variability of function calls need to consider both the variability of arguments directly given in the function and the variability of the used default arguments, if any.
+The variability of function calls needs to consider both the variability of arguments directly given in the function and the variability of the used default arguments, if any.
 This is especially a concern for functions given as a short class, see \cref{inheritance-of-functions}.
 This has additional implications for redeclarations, see \cref{function-compatibility}.