1. The problem asks: Today you drank $\frac{4}{5}$ of the water from your water bottle. Yesterday you drank $\frac{3}{5}$ of the water. On which day did you drink less water? Explain. 2. To compare the amounts of water drunk on the two days, note that both fractions have the same denominator 5. 3. When fractions have the same denominator, the fraction with the smaller numerator is the smaller fraction. 4. Compare the numerators: $4$ (today) and $3$ (yesterday). 5. Since $3 < 4$, $\frac{3}{5} < \frac{4}{5}$. 6. Therefore, you drank less water yesterday than today. Final answer: You drank less water yesterday because $\frac{3}{5} < \frac{4}{5}$.