$f(x + \sqrt x ) = x - \sqrt x $$f(380) = ?$ Thursday, January 06, 2022 Substituting 361 in place of x,$f(361 + \sqrt {361} ) = 361 - \sqrt {361} $$ \Rightarrow f(361 + 19) = 361 - 19$$ \Rightarrow f(380) = 342$