Hello! So, Luna mixed 3/4 cup of orange juice with 3/8 cup of cranberry juice. In this case, we add the the fractions together. Let's convert them into the same fraction. The LCM of 4 and 8 is 8. 3/4 is equivalent to 6/8. 6/8 + 3/8 is 9/8. Then, Luna gives 5/8 cup of juice to someone else. Now, we subtract. 9/8 - 5/8 is 4/8 or 1/2 in simplest form. 1/2 cup of juice is left in Luna's glass.
