The rate constant of a reaction becomes three times larger when the temperature rises from 288 K to…

Step 1. The temperature part. $\dfrac{1}{288\ \text{K}} - \dfrac{1}{298\ \text{K}} = 1.165 \times 10^{-4}\ \text{K}^{-1}$.

Step 2. Tripling. $E_a = \dfrac{8.314\ \text{J/(mol K)} \times \ln 3}{1.165 \times 10^{-4}\ \text{K}^{-1}} = \dfrac{8.314 \times 1.0986}{1.165 \times 10^{-4}}\ \text{J/mol} = 78\,400\ \text{J/mol}$.

Step 3. Doubling. $E_a = \dfrac{8.314 \times 0.6931}{1.165 \times 10^{-4}}\ \text{J/mol} = 49\,500\ \text{J/mol}$.