What are the mathematical expressions in the image?

Mathematical Expressions:

The image contains several mathematical expressions, primarily involving fractions and addition. Here are the expressions as they appear, with an attempt to interpret the characters:

• \( \frac{7}{15} + \frac{8}{3} \)
• \( \frac{4}{3} + \frac{5}{4} \)
• \( \frac{3}{7} + \frac{1}{5} \)
• \( \frac{4}{9} + \frac{5}{15} \)
• \( 5 \frac{7}{12} + 3 \frac{1}{4} \)
• \( 8 \frac{8}{15} + 10 \frac{3}{10} \)
• \( 3 \frac{3}{5} + 7 \frac{1}{6} \)
• \( 3 \frac{21}{5} + 1 \frac{6}{7} \)
• \( 1 \frac{17}{51} + 3 \frac{12}{51} \)

The letters preceding some expressions appear to be labels for these problems (e.g., 'o)', 'B)', 'r)', 'д)', 'e)', 'ж)', '3)', 'к)', 'л)').