Equation for percentage increase needed to equal overall percentage of classes

[callumst]

I have two classes: a and b. For arguments sake, the overall number of a's and b's is 100. So there are 10 A's, and 90 B's.
What equation can be used, to find out the percentage increase needed for the number of A's, to equal a set percentage overall?
E.g. I want A to represent 50% of the overall number of total A's and B's.
Where I am going wrong: So if I increase A by 500% I would get 50 A's. Then 50/(50+90) = 35.7%
Thanks (please move if its the wrong category sorry)

 

[stapel]

I have two classes: a and b. For arguments sake, the overall number of a's and b's is 100. So there are 10 A's, and 90 B's.

Your "so" does not follow from the "for argument's sake".

What equation can be used, to find out the percentage increase needed for the number of A's, to equal a set percentage overall? E.g. I want A to represent 50% of the overall number of total A's and B's.

Are you supposed to edit the number of inputs or the number of outputs?

Please reply with the full and exact text of the exercise, along with the complete instructions. Thank you!