Arecipe uses 2/3 cup of flour and 5/8 cup of blueberries. is there more flour or blueberries in the recipe?

In order to solve this, you must make sure that the denominators (bottom number) are the same. In this case, they are not. So you have to get them to be the same. The easiest way to do this is to multiply the denominators together. So you have 3x8=24. The denominator of these numbers are 24. Now that you changed the bottom, you must change the top. What did you multiply 3 by to get to 24? 8. So you have to multiply the top number by 8. On the other one, what did you multiply 8 by to get 24? 3. So multiply the top of that fraction by 3. So now you have 
16/24  or  15/24. In this case, the 16 is larger than the 15 so there is more flower than blueberries.