Heat And Thermodynamics

Two metal rods $A$ and $B$ each of length 50 cm can diameter 4.0 mm are joined together at temperature $30^{\circ} \mathrm{C}$. What is the change in length of the combined rod at $230^{\circ} \mathrm{C}$ ? (Given, linear expansion coefficients of rods $A$ and $B$ are respectively, $2.0 \times 10^{-5} /{ }^{\circ} \mathrm{C}$ and $1.0 \times 10^{-5} /{ }^{\circ} \mathrm{C}$ )