This can be solved by converting both fractions to a common denominator. The easiest way to find a common denominator is to multiply both denominators together. So, 3*8 is 24.
Next, convert the numerators. Multiply the numerator of each fraction by the old denominator of the other fraction.
Flour:
2/3 -> (2*8)/24 -> 16/24
Blueberries:
5/8 -> (5*3)/24 -> 15/24 ------ Because the numerator of flour, 16, is greater than that of blueberries, 15, and both fractions have the same denominator, the amount of flour is greater than the amount of blueberries in the recipe.
The second equation because they all have a common factor of 3. You can get x by itself. However, with the first one, you'll end up with fractions instead.