So in order to figure this out we need to know the difference between the 2 fractions. By doing this, you have to make sure that the denominators of both fractions are the same. So, they are the same, so we can move on to the numerators which is 5 and 8, and difference means subtracting.
5-3=2
So, 2/8 and the greater fraction was 5/8, so Darcy put more blueberries in each muffin (2/8 more).
Hope this helps! :)