The ratio of Melanie's allowance to Jacob's allowance is 4.1 to 20.5. If Jacob gets $5.00, how much allowance does Melanie get?

If Melanie get's 4.10$, then Jacob get's 20.50$.

We can divide to get the unit rate:

20.50 : 4.10 = 5

This means that if Jacob gets 5$, then Melanie will get 1$.

So in this case, Melanie get's 1$.