I am sure this is obvious but I am trying to figure it out bottom-up and have hit a wall.
$A$ is a fixed part of $B$ where $\frac{A}{B} = 0.25$. A is reduced by $20\%$ so that $B$ is reduced by $5\%$. Now $\frac{A}{B}$ is $0.2105$. Is there any rule here which explains the change in the ratio of $\frac{A}{B}$ for any change in $A$?
| Change in $A$ | $\frac{A}{B}$ |
|---|---|
| -10% | 0.2307 |
| -20% | 0.2105 |
| -30% | 0.1891 |
| -40% | 0.166 |
thank you.