The temperature of equal masses of three different liquids A, B and C are $12^\circ\text{C}$, $19^\circ\text{C}$ and $28^\circ\text{C}$ respectively. The temperature when A and B are mixed is $16^\circ\text{C}$ and when B and C are mixed is $23^\circ\text{C}$. The temperature when A and C are mixed is