We can add the fractions together to compare with how much sugar she needs.
[tex]\frac{1}{2}+\frac{2}{5}=\frac{5}{10}+\frac{4}{5}=\frac{9}{10}[/tex]
So Juvi has [tex]\frac{9}{10}[/tex] cups of sugar.
She needs [tex]\frac{2}{3}[/tex] cups, so let's make the denominators the same and compare.
[tex]\frac{2}{3}=\frac{20}{30}[/tex]
[tex]\frac{9}{10}=\frac{27}{30}[/tex]
Since [tex]\frac{27}{30}[/tex] > [tex]\frac{20}{30}[/tex], she has enough sugar to make 4 batches of brownies.
Hope this helps.
頑張って!