ничто

$Q^d_{общ}=\left\{\begin{matrix}80-\frac{56}{3}P,\ P\in{(0;3]}\\60-12P,\ P\in{(3;5]}\end{matrix}\right$

$Q^s=-20+20P$

$\left\{\begin{matrix}Q^s=Q^d=\frac{3680}{116}\\P^s=P^d=\frac{300}{116}\end{matrix}\right$