Actually you cant do this, if solution b is 0% percent acidic, the only thing you can do by addin b to a is the dilution. To concentrate from 30% to 54% the acidity of b should be greater than 54%.
This can be shown mathematically below.
The acidity of a = 30%
The acidity of b = 0%
The volume of a added = a
The volume of b added = b
`a+b = 800`
`30/100 xx a + 0/100 xx b = 54/100 xx 800`
`30a = 43200`
`a = 1440`
Therefore, `b = 800-1440 = -640.`
A volume cannot be negative, you cant make this happen.