When the business was worth $4.5 billion
Julie's share worth
= 4/(4 + 5 + 7) * $4.5 b
= 4/16 * $4.5b
= $1.125 billion
Annabelle share worth
= 5/16 * $4.5b
= $1.40625 billion
If Annabelle buys 50% of the worthof Julie's, her total share worth
= 50% * $1.125 billion + $1.40625 billion
= $1.96875 billion
This is equivalent in percentage as
= $1.96875 billion/$4.5 billion * 100%
= 43.75%
Since the business is now owned by Max and Annabelle, Max share worth
= 100% - 43.75%
= 56.25%