What is the value of f(n/2)?

$f(x)+2f(-x)=\sin(x)\\ f(-x)+2f(x) = \sin(-x) = -\sin(x) \\ \text{add these two equations} \\ 3(f(x)+f(-x)) = 0\\ f(-x)=-f(x)\\ f(x) -2f(x) = \sin(x) \\ -f(x) = \sin(x)\\ f(x) = -\sin(x) \\ f\left(\dfrac n 2\right) = -\sin\left(\dfrac n 2\right)$

thank you