5/7 + 3/4 + 15/28

Solution:
1. Given fractions:
\frac{5}{7}, \frac{3}{4}, \frac{15}{28}

2. Find the least common denominator (LCD):
- The denominators are 7, 4, 28.
- The LCD of 7, 4, \, \text{and} \, 28 is 28.

3. Convert each fraction to have the LCD of 28:
- \frac{5}{7} = \frac{5 \times 4}{7 \times 4} = \frac{20}{28}
- \frac{3}{4} = \frac{3 \times 7}{4 \times 7} = \frac{21}{28}
- \frac{15}{28} = \frac{15}{28}

4. Add the fractions together:
\frac{20}{28} + \frac{21}{28} + \frac{15}{28} = \frac{20 + 21 + 15}{28} = \frac{56}{28}

5. Simplify the fraction:
\frac{56}{28} = 2

The final answer is 2.