the recent 2015 Nepal earthquake was recorded to have had a magnitude of a 7.8 on the Richter scale.

In contrast the 1989 Loma Prieta earthquake was recorded to have had a magnitude of 6.9 on the Richter scale, how much more energy was released in the Nepal earthquake? In other words how much stronger was the nepal earthquake

Update: I do not know how accurate these numbers are I am just doing a math problem my teacher made up.

Can you please tell me if 28.8 is the correct answer?