How do I calculate 2 numbers as a percentage chart?

Say Google makes $23b a year in advertising and Yahoo makes $6b.

(Pretend for a second that MSN doesn't exist) In this scenario, two companies are the only 2 search engines. How would you calculate a percentage to say something like "Google makes ___% of all advertising revenue and Yahoo makes ____%?How do I calculate 2 numbers as a percentage chart?
Google = 23/ 29 x 100 = 79.31%



Yahoo = 6/29 x 100 = 20.69%How do I calculate 2 numbers as a percentage chart?
Divide Google's share ($23B) by the sum of all shares (23+6 = $29B) of advertising revenue, then multiply by 100 to get the percent.



23/(23+6) = 23/29 = 0.793*100 = 79.3%

So Google earns 79.3% of advertising revenue between it and Yahoo.