What is output?

double MyFct$($double a$,$ double b$)\{$

return $\frac{a+b}{2\mathrm{.}0}$;

$\}$

int main$()($

double $x=3\mathrm{.}0$;

double $y=5\mathrm{.}0$;

double $z=8\mathrm{.}0$;

double $t$;

$t=MyFct(x,y)$

$t=MyFct(t,z)$

cout $t$ endl;

return $$;

$\}$