Answer:
Brand b has the 5% of the market.
Explanation:
The first market scenario has three brands that share the market as follow:
Initial market share
Brand a 15%
Brand b 20%
Brand c 65%
Then brand d captures 30% of the market as Brand a and Brand b lost the relative same amount of market share. Meaning they both lost the 15% of their market share.
Brand d captures 30%
This capture leads to the following market share:
Final market share:
Brand a 0%
Brand b 5%
Brand c 65%
Brand d captures 30%
As the incursion of Brand d captured the total share of Brand a then, the Brand A has to left the market. Besides, the Brand b end up with a share of 5% of the total market share.