Degree Of Financial Leverage

In page 138, example 2, the solution didn`t made any sense for me, where does 30 billion of operating income came from?

Heres a image that maybe usefull for what Im talking about:

https://gyazo.com/1451b8452bb895d12954f0071ba5c0d5

Refer to Example 1 for the calculation of the 30 billion operating income.