An aluminium and steel rods having same lengths and cross-sections are joined to make total length of $120\text{ cm}$ at $30^\circ\text{C}$. The coefficient of linear expansion of aluminium and steel are $24 \times 10^{-6}/^\circ\text{C}$ and $1.2 \times 10^{-5}/^\circ\text{C}$, respectively. The length of this composite rod when its temperature is raised to $100^\circ\text{C}$, is _____ $\text{cm}$.