Before you can compare, you need to find common denominators. The common denominator of [tex] \frac{4}{5} [/tex] and [tex] \frac{2}{3} [/tex] is 15. So the fractions are now: [tex] \frac{12}{15} [/tex] and [tex] \frac{5}{15} [/tex]. Then subtract to find the difference:
[tex] \frac{12}{15} - \frac{5}{15} = \frac{7}{15} [/tex] more cups of sugar are needed.
Hope that helps.
