For hypothetical reversible reaction
$\frac{1}{2}A_{2}(g)+\frac{3}{2}B_{2}(g)\rightarrow AB_{3}(g)$, $\Delta H=-20~kJ$.
If standard entropies of $A_{2}$, $B_{2}$ and $AB_{3}$ are 60, 40 and 50 $JK^{-1}mol^{-1}$ respectively, then above reaction will be at equilibrium at temperature:

Question

For hypothetical reversible reaction 
$\frac{1}{2}A_{2}(g)+\frac{3}{2}B_{2}(g)\rightarrow AB_{3}(g)$, $\Delta H=-20~kJ$. 
If standard entropies of $A_{2}$, $B_{2}$ and $AB_{3}$ are 60, 40 and 50 $JK^{-1}mol^{-1}$ respectively, then above reaction will be at equilibrium at temperature: