A reaction takes place in three steps with activation energy $E_{a_1}=180 \mathrm{kJ}/\mathrm{mol},{\overline{\mathit{ }E}}_{a_2}=80 \mathrm{kJ}/\mathrm{mol}, {\mathrm{E}}_{a_9}=50 \mathrm{kJ}/\mathrm{mol}$ respectively overall rate contestant of the reaction is $k={\left[\frac{k_1{k}_2}{k_3}\right]}^{2/3}$ the overall activation energy of reaction will be (Here $k_1,k_2$ and $k_3$ a rate constant of first, second and third step respectively.) :