
$A_{1}=2 A, A_{2}=A$
$\mathrm{T}_{1}=100^{\circ} \mathrm{C}$ and $\mathrm{T}_{2}=70^{\circ} \mathrm{C}$
$\therefore$ Temperature at $\mathrm{C}$ be $\mathrm{T},$ then
$\frac{\Delta Q}{\Delta t}=\frac{K 2 A(100-T)}{1}=\frac{K A(T-70)}{1}$
or $T=90^{\circ} \mathrm{C}$

