\( \begin{array}{lll}\text { (4) } \frac{2}{3}+\frac{7}{3} & \text { (5) }-\frac{1}{2}+-\frac{1}{3} & \text { (6) } 4+\frac{1}{2} \\ \text { (7) } \frac{7}{15}+\frac{21}{10} & \text { (8) } \frac{2}{3}+2 & \text { (9) } \frac{2}{3}+3 \\ \text { (10) } 4+\frac{4}{3} & \text { (11) }-10+\frac{5}{7} & \text { (12) }-\frac{5}{8}+-25 \\ \text { (13) } 1 \frac{1}{3}+1 \frac{1}{2} & \text { (14) } 1 \frac{1}{4}+1 \frac{2}{3} & \text { (15) } 1 \frac{1}{7}+2\end{array} \)

Let’s dive into some interesting points! Adding fractions is a skill that traces back to ancient civilizations! For example, Egyptians used unit fractions (fractions with a numerator of one) in their math, demonstrating just how integral adding fractions has been throughout history. It’s fascinating to think that the same operations we use today have roots that date back thousands of years! In real-world scenarios, adding fractions is often seen in cooking and baking. Recipes frequently require adjusting ingredient amounts that are fractional, making fraction addition essential! For instance, if a recipe calls for \( \frac{1}{2} \) cup of sugar and you want to add \( \frac{1}{4} \) more, you'd quickly discover that you’ll need to add those fractions together to get your total - which is \( \frac{3}{4} \) cup of sugar!