we have that $a=2b$ where $a$ is the income of $A$ and $b$ the income of $B$.
I want to write statements about the percentages that we get from that.
Since $b$ is the half of $a$ we can say that the income of $B$ is by $50\%$ less than the income of $A$, right?
What statement do we get for the other direction?
I mean : The income of $A$ is by $x\%$ more than the income of $B$.
Which number is $x$ ?
The statement you wanted to write is correct.
If you take income of B 100 then income of A is 200. So, income of A is 100% more than that of B.